diff --git a/scripts/migrations/014-product-prices.ts b/scripts/migrations/014-product-prices.ts
new file mode 100644
index 0000000..6c12c12
--- /dev/null
+++ b/scripts/migrations/014-product-prices.ts
@@ -0,0 +1,10 @@
+import { ProductPriceModel } from "@/models/product-price";
+import type { Migration } from "./types";
+
+export const migration: Migration = {
+  name: "014-product-prices",
+  description: "ürün fiyat kayıtları (productPrices) index'leri",
+  async up() {
+    await ProductPriceModel.createIndexes();
+  },
+};
diff --git a/scripts/migrations/index.ts b/scripts/migrations/index.ts
index d90024a..dc8e080 100644
--- a/scripts/migrations/index.ts
+++ b/scripts/migrations/index.ts
@@ -13,6 +13,7 @@ import { migration as m010 } from "./010-budgets";
 import { migration as m011 } from "./011-stock";
 import { migration as m012 } from "./012-stock-counts";
 import { migration as m013 } from "./013-stores-products";
+import { migration as m014 } from "./014-product-prices";
 import type { Migration } from "./types";
 
 /** Sıralı migration listesi. Yeni migration: dosyayı ekle ve buraya sırayla ekle. */
@@ -30,6 +31,7 @@ export const MIGRATIONS: Migration[] = [
   m011,
   m012,
   m013,
+  m014,
 ];
 
 const COLLECTION = "migrations";
diff --git a/scripts/seed/run.int.test.ts b/scripts/seed/run.int.test.ts
index 92b7dc6..a3e466a 100644
--- a/scripts/seed/run.int.test.ts
+++ b/scripts/seed/run.int.test.ts
@@ -37,6 +37,7 @@ describe("seed", () => {
     expect(summary.created.stock).toBe(19);
     expect(summary.created.stores).toBe(8);
     expect(summary.created.products).toBe(22);
+    expect(summary.created.prices).toBeGreaterThan(200);
     expect(await getDb().collection("user").countDocuments()).toBe(SEED_USERS.length + 1);
     expect(await HouseholdMemberModel.countDocuments()).toBe(memberCount);
   });
@@ -59,6 +60,7 @@ describe("seed", () => {
       stock: 0,
       stores: 0,
       products: 0,
+      prices: 0,
     });
     expect(await getDb().collection("user").countDocuments()).toBe(SEED_USERS.length + 1);
     expect(await HouseholdModel.countDocuments()).toBe(SEED_HOUSEHOLDS.length);
diff --git a/scripts/seed/run.ts b/scripts/seed/run.ts
index 284a447..0227767 100644
--- a/scripts/seed/run.ts
+++ b/scripts/seed/run.ts
@@ -13,7 +13,7 @@ import { runMigrations } from "../migrations";
 import { seedContacts } from "./contacts";
 import { seedAssets } from "./assets";
 import { seedBudgets } from "./budgets";
-import { seedShopping } from "./shopping";
+import { seedProductPrices, seedShopping } from "./shopping";
 import { seedStock } from "./stock";
 import { seedInKind } from "./in-kind";
 import { seedInstallments } from "./installments";
@@ -60,6 +60,7 @@ export type SeedSummary = {
     stock: number;
     stores: number;
     products: number;
+    prices: number;
   };
   accounts: SeedAccountRow[];
 };
@@ -89,6 +90,7 @@ const DOMAIN_COLLECTIONS = [
   "stockCounts",
   "stores",
   "products",
+  "productPrices",
 ];
 
 type AuthApi = ReturnType<typeof getAuth>["api"];
@@ -147,6 +149,7 @@ export async function runSeed({
       stock: 0,
       stores: 0,
       products: 0,
+      prices: 0,
     },
     accounts: [],
   };
@@ -336,6 +339,8 @@ export async function runSeed({
   summary.created.products = shopping.products;
   if (shopping.stores || shopping.products)
     log(`✓ Örnek mağazalar ve ürünler: ${shopping.stores} / ${shopping.products}`);
+  summary.created.prices = await seedProductPrices(householdIds, userIdMap);
+  if (summary.created.prices) log(`✓ Örnek ürün fiyatları: ${summary.created.prices}`);
 
   // 7) Geliştirme hesapları tablosu
   const all = [
diff --git a/scripts/seed/shopping.ts b/scripts/seed/shopping.ts
index cdabf25..52da88f 100644
--- a/scripts/seed/shopping.ts
+++ b/scripts/seed/shopping.ts
@@ -1,9 +1,12 @@
 import { Types } from "mongoose";
 import { ProductModel } from "@/models/product";
+import { ProductPriceModel } from "@/models/product-price";
 import { ProductTypeModel } from "@/models/product-type";
 import { StoreModel } from "@/models/store";
 import type { MealCardProvider } from "@/shared/accounts";
 import { autoConvertible } from "@/shared/products";
+import { todayIstanbul } from "@/shared/dates";
+import { addDays } from "@/shared/recurrence";
 import { foldTr } from "@/shared/search";
 import type { StoreKind } from "@/shared/stores";
 
@@ -326,3 +329,166 @@ export async function seedShopping(
   }
   return { stores, products };
 }
+
+// --- Fiyatlar (Faz 12b) ---
+
+/** Bugünkü paket fiyatı (kuruş, Kasım 2026 tahmini). */
+const CURRENT_PRICE: Record<string, number> = {
+  "ariel-5kg": 519_90,
+  "omo-6kg": 559_90,
+  "bingo-4kg": 329_90,
+  "fairy-50": 479_90,
+  "finish-40": 419_90,
+  "yayla-mercimek": 84_90,
+  "reis-mercimek": 79_90,
+  "duru-mercimek": 189_90,
+  "yayla-baldo": 259_90,
+  "reis-baldo": 109_90,
+  "pinar-sut": 41_90,
+  "sutas-sut": 39_90,
+  "icim-sut-500": 23_90,
+  "keskinoglu-30": 174_90,
+  "koy-yumurta-15": 119_90,
+  "pinar-peynir": 209_90,
+  "yumos-1440": 139_90,
+  "selpak-32": 329_90,
+  "solo-24": 229_90,
+  "colgate-75": 84_90,
+  "sensodyne-75": 159_90,
+  "elidor-500": 119_90,
+};
+
+/** Mağaza fiyat çarpanı (indirim marketi ucuz, online pahalı). */
+const STORE_FACTOR: Record<string, number> = {
+  migros: 1.06,
+  a101: 0.94,
+  bim: 0.91,
+  sok: 0.96,
+  carrefoursa: 1.0,
+  "getir-buyuk": 1.12,
+  metro: 0.88,
+};
+const PRICE_STORES = Object.keys(STORE_FACTOR);
+/** Aylık fiyat artışı. */
+const MONTHLY_INFLATION = 0.025;
+
+/** x,90 biçimine yuvarla (ör. 87,34 → 86,90 / 87,90). */
+const ninety = (minor: number) => Math.max(90, Math.round((minor - 90) / 100) * 100 + 90);
+
+type SeedPrice = {
+  ref: string;
+  product: string;
+  store: string;
+  daysAgo: number;
+  priceMinor: number;
+  isPromo?: boolean;
+  promoUntilDaysAgo?: number;
+};
+
+/**
+ * Her ürün 3 mağazada (ürün sırasına göre dönüşümlü), son 6 ayda ~45 günde bir fiyat.
+ * Kampanyalar: Ariel @ Migros hâlâ süren (%20), Pınar süt @ A101 süresi bitmiş (önceki normal
+ * fiyata dönülür). Reis mercimek @ Metro yalnızca eski kayıtlarla ("eski fiyat").
+ */
+export function seedPrices(): SeedPrice[] {
+  const out: SeedPrice[] = [];
+  PRODUCTS.forEach((p, i) => {
+    const current = CURRENT_PRICE[p.ref]!;
+    const stores = [0, 2, 4].map((k) => PRICE_STORES[(i + k) % PRICE_STORES.length]!);
+    stores.forEach((store, si) => {
+      for (let step = 0; step < 4; step++) {
+        const daysAgo = 170 - step * 45 - si * 7 - (i % 5);
+        if (daysAgo < 0) continue;
+        if (p.ref === "reis-mercimek" && store === "metro" && daysAgo < 100) continue;
+        const months = daysAgo / 30;
+        const price = (current * STORE_FACTOR[store]!) / (1 + MONTHLY_INFLATION) ** months;
+        out.push({
+          ref: `${p.ref}:${store}:${step}`,
+          product: p.ref,
+          store,
+          daysAgo,
+          priceMinor: ninety(price),
+        });
+      }
+    });
+  });
+  out.push(
+    {
+      ref: "ariel-5kg:migros:promo",
+      product: "ariel-5kg",
+      store: "migros",
+      daysAgo: 4,
+      priceMinor: ninety(CURRENT_PRICE["ariel-5kg"]! * 1.06 * 0.8),
+      isPromo: true,
+      promoUntilDaysAgo: -6,
+    },
+    {
+      ref: "pinar-sut:a101:normal",
+      product: "pinar-sut",
+      store: "a101",
+      daysAgo: 30,
+      priceMinor: ninety(CURRENT_PRICE["pinar-sut"]! * 0.94),
+    },
+    {
+      ref: "pinar-sut:a101:promo",
+      product: "pinar-sut",
+      store: "a101",
+      daysAgo: 12,
+      priceMinor: ninety(CURRENT_PRICE["pinar-sut"]! * 0.75),
+      isPromo: true,
+      promoUntilDaysAgo: 3,
+    },
+  );
+  return out;
+}
+
+export async function seedProductPrices(
+  householdIds: Map<string, Types.ObjectId>,
+  users: Map<string, string>,
+): Promise<number> {
+  const actor = new Types.ObjectId(users.get("ayse")!);
+  const householdId = householdIds.get("Çakır Ailesi")!;
+  const [products, stores] = await Promise.all([
+    ProductModel.find({ householdId, seedRef: { $type: "string" } })
+      .select({ seedRef: 1 })
+      .lean<{ _id: Types.ObjectId; seedRef: string }[]>(),
+    StoreModel.find({ householdId, seedRef: { $type: "string" } })
+      .select({ seedRef: 1 })
+      .lean<{ _id: Types.ObjectId; seedRef: string }[]>(),
+  ]);
+  const productByRef = new Map(products.map((p) => [p.seedRef, p._id]));
+  const storeByRef = new Map(stores.map((x) => [x.seedRef, x._id]));
+  const existing = new Set(
+    (
+      await ProductPriceModel.find({ householdId, seedRef: { $type: "string" } })
+        .select({ seedRef: 1 })
+        .lean<{ seedRef: string }[]>()
+    ).map((x) => x.seedRef),
+  );
+  const today = todayIstanbul();
+  const base = Date.now() - 200 * 86_400_000;
+  const docs = seedPrices()
+    .filter((x) => !existing.has(x.ref) && productByRef.has(x.product) && storeByRef.has(x.store))
+    .sort((a, b) => b.daysAgo - a.daysAgo)
+    .map((x, i) => {
+      const at = new Date(base + i * 1000);
+      return {
+        householdId,
+        productId: productByRef.get(x.product)!,
+        storeId: storeByRef.get(x.store)!,
+        date: addDays(today, -x.daysAgo),
+        priceMinor: x.priceMinor,
+        isPromo: x.isPromo ?? false,
+        promoUntil: x.promoUntilDaysAgo === undefined ? null : addDays(today, -x.promoUntilDaysAgo),
+        source: "manual",
+        note: "",
+        deletedAt: null,
+        seedRef: x.ref,
+        createdBy: actor,
+        createdAt: at,
+        updatedAt: at,
+      };
+    });
+  if (docs.length) await ProductPriceModel.collection.insertMany(docs);
+  return docs.length;
+}
diff --git a/src/features/prices/actions.ts b/src/features/prices/actions.ts
new file mode 100644
index 0000000..70e489e
--- /dev/null
+++ b/src/features/prices/actions.ts
@@ -0,0 +1,44 @@
+"use server";
+
+import { revalidatePath } from "next/cache";
+import { z } from "zod";
+import { tr } from "@/i18n/tr";
+import { fail, type ActionResult } from "@/lib/action-result";
+import { getHouseholdActionContext } from "@/lib/dal";
+import { productPriceFormSchema } from "@/shared/schemas/product-price";
+import { addProductPrice, deleteProductPrice } from "./service";
+
+const idSchema = z.string().regex(/^[a-f0-9]{24}$/i);
+
+function fieldErrors(error: z.ZodError) {
+  const out: Record<string, string> = {};
+  for (const issue of error.issues) {
+    const key = issue.path.join(".");
+    if (key && !out[key]) out[key] = issue.message;
+  }
+  return out;
+}
+
+async function run<T, R>(
+  schema: z.ZodType<T>,
+  input: unknown,
+  fn: (userId: string, householdId: string, data: T) => Promise<ActionResult<R>>,
+): Promise<ActionResult<R>> {
+  const ctx = await getHouseholdActionContext("member");
+  if (!ctx) return fail(tr.common.unauthorized);
+  const parsed = schema.safeParse(input);
+  if (!parsed.success) return fail(tr.adminUsers.errors.checkFields, fieldErrors(parsed.error));
+  const result = await fn(ctx.user.id, ctx.household.id, parsed.data);
+  if (result.ok) revalidatePath("/", "layout");
+  return result;
+}
+
+export async function addProductPriceAction(input: unknown) {
+  return run(productPriceFormSchema, input, (u, h, d) => addProductPrice(u, h, d));
+}
+
+export async function deleteProductPriceAction(priceId: unknown) {
+  const id = idSchema.safeParse(priceId);
+  if (!id.success) return fail(tr.common.notFound);
+  return run(z.unknown(), null, (u, h) => deleteProductPrice(u, h, id.data));
+}
diff --git a/src/features/prices/options.ts b/src/features/prices/options.ts
new file mode 100644
index 0000000..1f045ce
--- /dev/null
+++ b/src/features/prices/options.ts
@@ -0,0 +1,18 @@
+import type { ProductView } from "@/features/products/service";
+
+/** Fiyat formu ürün seçeneği (birim fiyat önizlemesi için dönüşümle). İstemcide de kullanılır. */
+export type PriceProductOption = {
+  id: string;
+  label: string;
+  packageLabel: string;
+  inTypeUnit: number | null;
+  typeUnit: string;
+};
+
+export const priceProductOption = (p: ProductView): PriceProductOption => ({
+  id: p.id,
+  label: p.label,
+  packageLabel: p.packageLabel,
+  inTypeUnit: p.inTypeUnit,
+  typeUnit: p.typeUnit,
+});
diff --git a/src/features/prices/service.int.test.ts b/src/features/prices/service.int.test.ts
new file mode 100644
index 0000000..4cfe4bc
--- /dev/null
+++ b/src/features/prices/service.int.test.ts
@@ -0,0 +1,150 @@
+import { afterAll, beforeAll, describe, expect, it } from "vitest";
+import { getStockAnalysis } from "@/features/stock/service";
+import { AuditLogModel } from "@/models/audit-log";
+import { ProductModel } from "@/models/product";
+import { ProductTypeModel } from "@/models/product-type";
+import { StoreModel } from "@/models/store";
+import { todayIstanbul } from "@/shared/dates";
+import { addDays } from "@/shared/recurrence";
+import { productPriceFormSchema } from "@/shared/schemas/product-price";
+import { setupSeededDb, teardownDb } from "@/test/seeded-db";
+import {
+  addProductPrice,
+  deleteProductPrice,
+  getProductPrices,
+  getTypePriceComparison,
+} from "./service";
+
+let ids: Awaited<ReturnType<typeof setupSeededDb>>;
+let cakir = "";
+let ayse = "";
+let zeynep = "";
+let fatma = "";
+const today = todayIstanbul();
+
+beforeAll(async () => {
+  ids = await setupSeededDb();
+  cakir = ids.household("Çakır Ailesi");
+  ayse = ids.user("ayse");
+  zeynep = ids.user("zeynep");
+  fatma = ids.user("fatma");
+});
+afterAll(teardownDb);
+
+const ref = (
+  model: typeof ProductModel | typeof StoreModel | typeof ProductTypeModel,
+  seedRef: string,
+) =>
+  (model as typeof ProductModel)
+    .findOne({ seedRef })
+    .lean()
+    .then((x) => String(x!._id));
+
+describe("birim fiyat karşılaştırması", () => {
+  it("toz deterjan: birim fiyata göre sıralı, en uygun işaretli, süren kampanya", async () => {
+    const c = (await getTypePriceComparison(
+      ayse,
+      cakir,
+      await ref(ProductTypeModel, "toz-deterjan"),
+    ))!;
+    expect(c.typeUnit).toBe("yıkama");
+    const units = c.offers.map((o) => o.unitPriceMinor!);
+    expect(units).toEqual([...units].sort((a, b) => a - b));
+    expect(c.offers[0]!.cheapest).toBe(true);
+    expect(c.offers.filter((o) => o.cheapest)).toHaveLength(1);
+    const ariel = c.offers.find(
+      (o) => o.productLabel.startsWith("Ariel") && o.store.label.startsWith("Migros"),
+    )!;
+    expect(ariel.price).toMatchObject({ isPromo: true, promoUntil: addDays(today, 6) });
+    expect(ariel.promoEnded).toBe(false);
+    // Birim fiyat = paket / 33 yıkama.
+    expect(ariel.unitPriceMinor!).toBeCloseTo((ariel.price.priceMinor * 1000) / 33_000, 6);
+    expect(c.products).toHaveLength(3);
+    expect(
+      await getTypePriceComparison(fatma, cakir, await ref(ProductTypeModel, "toz-deterjan")),
+    ).toBeNull();
+  });
+
+  it("süresi biten kampanyada normal fiyata dönülür; eski fiyat işaretlenir", async () => {
+    const sut = (await getProductPrices(ayse, cakir, await ref(ProductModel, "pinar-sut")))!;
+    const a101 = sut.offers.find((o) => o.store.label.startsWith("A101"))!;
+    expect(a101).toMatchObject({ fellBack: true, promoEnded: false });
+    expect(a101.price.isPromo).toBe(false);
+    expect(a101.price.date).toBe(addDays(today, -30));
+    expect(sut.history.some((h) => h.isPromo && h.promoEnded)).toBe(true);
+    expect(sut.series.length).toBeGreaterThanOrEqual(3);
+    expect(sut.points.length).toBeGreaterThan(5);
+
+    const reis = (await getProductPrices(ayse, cakir, await ref(ProductModel, "reis-mercimek")))!;
+    expect(reis.offers.find((o) => o.store.label.startsWith("Metro"))!.stale).toBe(true);
+  });
+});
+
+describe("fiyat girişi", () => {
+  it("ekle, gelecek tarih ve arşivli mağaza reddi, izleyici yazamaz, sil + denetim", async () => {
+    const productId = await ref(ProductModel, "omo-6kg");
+    const storeId = await ref(StoreModel, "sok");
+    const form = (over: Record<string, unknown> = {}) =>
+      productPriceFormSchema.parse({
+        productId,
+        storeId,
+        date: today,
+        price: "449,90",
+        isPromo: false,
+        promoUntil: "",
+        note: "",
+        ...over,
+      });
+    expect(
+      productPriceFormSchema.safeParse({ ...form(), price: "0", isPromo: false }).success,
+    ).toBe(false);
+    expect(
+      productPriceFormSchema.safeParse({
+        productId,
+        storeId,
+        date: today,
+        price: "10",
+        isPromo: true,
+        promoUntil: addDays(today, -1),
+      }).success,
+    ).toBe(false);
+
+    expect((await addProductPrice(ayse, cakir, form({ date: addDays(today, 1) }))).ok).toBe(false);
+    expect((await addProductPrice(zeynep, cakir, form())).ok).toBe(false);
+
+    const r = await addProductPrice(ayse, cakir, form());
+    expect(r.ok).toBe(true);
+    let d = (await getProductPrices(ayse, cakir, productId))!;
+    const sok = d.offers.find((o) => o.store.id === storeId)!;
+    expect(sok.price).toMatchObject({ priceMinor: 449_90, date: today, source: "manual" });
+    // 6 kg = 40 yıkama → 11,2475 TL/yıkama.
+    expect(sok.unitPriceMinor).toBeCloseTo(1124.75, 6);
+
+    const priceId = r.ok ? r.data.id : "";
+    expect((await deleteProductPrice(fatma, cakir, priceId)).ok).toBe(false);
+    expect((await deleteProductPrice(ayse, cakir, priceId)).ok).toBe(true);
+    expect(await AuditLogModel.exists({ action: "price.delete", targetId: priceId })).toBeTruthy();
+    d = (await getProductPrices(ayse, cakir, productId))!;
+    expect(d.history.some((h) => h.id === priceId)).toBe(false);
+
+    await StoreModel.updateOne({ _id: storeId }, { $set: { archivedAt: new Date() } });
+    expect(await addProductPrice(ayse, cakir, form())).toMatchObject({
+      ok: false,
+      fieldErrors: { storeId: expect.any(String) },
+    });
+    await StoreModel.updateOne({ _id: storeId }, { $set: { archivedAt: null } });
+  });
+});
+
+describe("tüketim analizinde maliyet", () => {
+  it("aylık ortalama tüketim × son birim fiyat", async () => {
+    const a = (await getStockAnalysis(ayse, cakir))!;
+    const deterjan = a.rows.find((r) => r.name === "Toz Deterjan")!;
+    expect(deterjan.unitPrice).not.toBeNull();
+    // Maliyet yuvarlanmamış ortalamadan; gösterilen ortalama yuvarlıdır (≤ %1 fark).
+    const expected = (deterjan.avgMonthlyUsed! * deterjan.unitPrice!.minor) / 1000;
+    expect(Math.abs(deterjan.avgMonthlyCostMinor! - expected) / expected).toBeLessThan(0.01);
+    // Ürünü (marka/paket) olmayan tipte maliyet yok.
+    expect(a.rows.find((r) => r.name === "Domates")!.avgMonthlyCostMinor).toBeNull();
+  });
+});
diff --git a/src/features/prices/service.ts b/src/features/prices/service.ts
new file mode 100644
index 0000000..a510386
--- /dev/null
+++ b/src/features/prices/service.ts
@@ -0,0 +1,436 @@
+import "server-only";
+import { Types } from "mongoose";
+import { hasHouseholdRole } from "@/features/households/roles";
+import { resolveMembership, type Membership } from "@/features/households/service";
+import { listProducts, type ProductView } from "@/features/products/service";
+import { storeLabel } from "@/features/stores/service";
+import { priceProductOption, type PriceProductOption } from "./options";
+import { tr } from "@/i18n/tr";
+import { fail, ok, type ActionResult } from "@/lib/action-result";
+import { writeAudit } from "@/lib/audit";
+import { toObjectId } from "@/lib/object-id";
+import { ProductModel } from "@/models/product";
+import { ProductPriceModel } from "@/models/product-price";
+import { ProductTypeModel } from "@/models/product-type";
+import { StoreModel } from "@/models/store";
+import { todayIstanbul } from "@/shared/dates";
+import {
+  effectivePrice,
+  promoEnded,
+  rankOffers,
+  seriesSlot,
+  unitPrice,
+  type PriceSource,
+  type RankedOffer,
+} from "@/shared/prices";
+import { packageInTypeUnit } from "@/shared/products";
+import type { ProductPriceForm } from "@/shared/schemas/product-price";
+import { compareTr } from "@/shared/search";
+
+/**
+ * Ürün fiyatları (Bölüm 6.11). Hane bazlı; okuma viewer, yazma member. Birim fiyat ürünün
+ * dönüşümüyle okuma sırasında hesaplanır (saf motor: shared/prices).
+ */
+
+const t = tr.productPrices;
+
+type PriceLean = {
+  _id: Types.ObjectId;
+  productId: Types.ObjectId;
+  storeId: Types.ObjectId;
+  date: string;
+  priceMinor: number;
+  isPromo: boolean;
+  promoUntil: string | null;
+  source: PriceSource;
+  note: string;
+  createdAt: Date;
+};
+
+type StoreLean = {
+  _id: Types.ObjectId;
+  name: string;
+  branch: string;
+  archivedAt: Date | null;
+  createdAt: Date;
+};
+
+export type StoreRef = { id: string; label: string; slot: number; archived: boolean };
+
+export type PriceRow = {
+  id: string;
+  productId: string;
+  store: StoreRef;
+  date: string;
+  priceMinor: number;
+  isPromo: boolean;
+  promoUntil: string | null;
+  promoEnded: boolean;
+  source: PriceSource;
+  note: string;
+  /** Ürün tipi biriminde 1 birimin fiyatı (kesirli kuruş; dönüşüm yoksa null). */
+  unitPriceMinor: number | null;
+};
+
+export type StoreOffer = {
+  /** Teklif anahtarı: ürün + mağaza. */
+  key: string;
+  productId: string;
+  productLabel: string;
+  packageLabel: string;
+  store: StoreRef;
+  price: PriceRow;
+  /** Son kayıt süresi biten kampanyaydı; önceki normal fiyat gösteriliyor. */
+  fellBack: boolean;
+  promoEnded: boolean;
+  ageDays: number;
+  stale: boolean;
+  unitPriceMinor: number | null;
+};
+
+export type ProductPriceDetail = {
+  product: ProductView;
+  offers: RankedOffer<StoreOffer>[];
+  /** Tüm kayıtlar, yeniden eskiye. */
+  history: PriceRow[];
+  /** Grafik: mağaza serileri ve tarih noktaları (paket fiyatı, kuruş). */
+  series: StoreRef[];
+  points: Record<string, number | string>[];
+  stores: StoreRef[];
+  canWrite: boolean;
+  today: string;
+};
+
+export type TypePriceComparison = {
+  typeUnit: string;
+  offers: RankedOffer<StoreOffer>[];
+  /** Fiyat girişi seçenekleri. */
+  products: PriceProductOption[];
+  stores: StoreRef[];
+  canWrite: boolean;
+};
+
+/** Hanenin tüm mağazaları; renk yuvası ekleniş sırasına göre sabit. */
+async function loadStores(householdId: Types.ObjectId) {
+  const rows = await StoreModel.find({ householdId })
+    .select({ name: 1, branch: 1, archivedAt: 1, createdAt: 1 })
+    .sort({ createdAt: 1, _id: 1 })
+    .lean<StoreLean[]>();
+  return new Map(
+    rows.map((s, i) => [
+      String(s._id),
+      {
+        id: String(s._id),
+        label: storeLabel(s),
+        slot: seriesSlot(i),
+        archived: Boolean(s.archivedAt),
+      } satisfies StoreRef,
+    ]),
+  );
+}
+
+const sortRecords = (a: PriceLean, b: PriceLean) =>
+  a.date === b.date ? a.createdAt.getTime() - b.createdAt.getTime() : a.date < b.date ? -1 : 1;
+
+async function loadPrices(householdId: Types.ObjectId, productIds: Types.ObjectId[]) {
+  const rows = await ProductPriceModel.find({
+    householdId,
+    productId: { $in: productIds },
+    deletedAt: null,
+  }).lean<PriceLean[]>();
+  return rows.sort(sortRecords);
+}
+
+function toRow(r: PriceLean, store: StoreRef, inTypeUnit: number | null, today: string): PriceRow {
+  return {
+    id: String(r._id),
+    productId: String(r.productId),
+    store,
+    date: r.date,
+    priceMinor: r.priceMinor,
+    isPromo: r.isPromo,
+    promoUntil: r.promoUntil,
+    promoEnded: promoEnded(r, today),
+    source: r.source,
+    note: r.note,
+    unitPriceMinor: inTypeUnit ? unitPrice(r.priceMinor, inTypeUnit) : null,
+  };
+}
+
+/** Ürün × mağaza başına geçerli fiyat teklifleri (sıralanmamış). */
+function offersFor(
+  products: ProductView[],
+  prices: PriceLean[],
+  stores: Map<string, StoreRef>,
+  today: string,
+): StoreOffer[] {
+  const groups = new Map<string, PriceLean[]>();
+  for (const r of prices) {
+    const key = `${r.productId}:${r.storeId}`;
+    groups.set(key, [...(groups.get(key) ?? []), r]);
+  }
+  const byId = new Map(products.map((p) => [p.id, p]));
+  const out: StoreOffer[] = [];
+  for (const [key, records] of groups) {
+    const p = byId.get(String(records[0]!.productId));
+    const store = stores.get(String(records[0]!.storeId));
+    if (!p || !store) continue;
+    const eff = effectivePrice(records, today)!;
+    const row = toRow(eff.record, store, p.inTypeUnit, today);
+    out.push({
+      key,
+      productId: p.id,
+      productLabel: p.label,
+      packageLabel: p.packageLabel,
+      store,
+      price: row,
+      fellBack: eff.fellBack,
+      promoEnded: eff.promoEnded,
+      ageDays: eff.ageDays,
+      stale: eff.stale,
+      unitPriceMinor: row.unitPriceMinor,
+    });
+  }
+  return out;
+}
+
+const activeStores = (stores: Map<string, StoreRef>) =>
+  [...stores.values()].filter((s) => !s.archived).sort((a, b) => compareTr(a.label, b.label));
+
+/** /stok/urunler/:id — ürünün mağaza bazında fiyatları, geçmişi ve grafiği. */
+export async function getProductPrices(
+  userId: string,
+  householdId: string,
+  productId: string,
+): Promise<ProductPriceDetail | null> {
+  const m = await resolveMembership(userId, householdId, "viewer");
+  if (!m) return null;
+  const id = toObjectId(productId);
+  if (!id) return null;
+  const doc = await ProductModel.findOne({ _id: id, householdId: m.householdId })
+    .select({ productTypeId: 1 })
+    .lean<{ productTypeId: Types.ObjectId }>();
+  if (!doc) return null;
+  const list = await listProducts(userId, householdId, {
+    productTypeId: String(doc.productTypeId),
+    includeArchived: true,
+  });
+  const product = list?.products.find((p) => p.id === productId);
+  if (!product) return null;
+  const today = todayIstanbul();
+  const [stores, prices] = await Promise.all([
+    loadStores(m.householdId),
+    loadPrices(m.householdId, [id]),
+  ]);
+  const history = prices
+    .map((r) => toRow(r, stores.get(String(r.storeId))!, product.inTypeUnit, today))
+    .filter((r) => r.store)
+    .reverse();
+  const seriesIds = [...new Set(prices.map((r) => String(r.storeId)))];
+  const series = seriesIds
+    .map((sid) => stores.get(sid)!)
+    .filter(Boolean)
+    .sort((a, b) => a.slot - b.slot);
+  // Aynı gün aynı mağazada birden çok kayıt: son giriş geçerli.
+  const byDate = new Map<string, Record<string, number | string>>();
+  for (const r of prices) {
+    const point = byDate.get(r.date) ?? { date: r.date };
+    point[`s${String(r.storeId)}`] = r.priceMinor;
+    byDate.set(r.date, point);
+  }
+  // Son nokta bugün: her mağazanın geçerli fiyatı (çizgi bugüne uzar; biten kampanyada normal fiyat).
+  const offers = offersFor([product], prices, stores, today);
+  if (offers.length) {
+    const point = byDate.get(today) ?? { date: today };
+    for (const o of offers) point[`s${o.store.id}`] ??= o.price.priceMinor;
+    byDate.set(today, point);
+  }
+  return {
+    product,
+    offers: rankOffers(offers),
+    history,
+    series,
+    points: [...byDate.values()].sort((a, b) => (String(a.date) < String(b.date) ? -1 : 1)),
+    stores: activeStores(stores),
+    canWrite: hasHouseholdRole(m.role, "member"),
+    today,
+  };
+}
+
+/** Ürün tipi detayı: tüm marka/paket ve mağazalar birim fiyata göre. */
+export async function getTypePriceComparison(
+  userId: string,
+  householdId: string,
+  productTypeId: string,
+): Promise<TypePriceComparison | null> {
+  const m = await resolveMembership(userId, householdId, "viewer");
+  if (!m) return null;
+  const list = await listProducts(userId, householdId, { productTypeId });
+  if (!list) return null;
+  const type = await ProductTypeModel.findOne({
+    _id: new Types.ObjectId(productTypeId),
+    householdId: m.householdId,
+  })
+    .select({ unit: 1 })
+    .lean<{ unit: string }>();
+  if (!type) return null;
+  const today = todayIstanbul();
+  const [stores, prices] = await Promise.all([
+    loadStores(m.householdId),
+    loadPrices(
+      m.householdId,
+      list.products.map((p) => new Types.ObjectId(p.id)),
+    ),
+  ]);
+  return {
+    typeUnit: type.unit,
+    offers: rankOffers(
+      offersFor(list.products, prices, stores, today).filter((o) => !o.store.archived),
+    ),
+    products: list.products.map(priceProductOption),
+    stores: activeStores(stores),
+    canWrite: list.canWrite,
+  };
+}
+
+/**
+ * Ürün tipi başına son bilinen birim fiyat (en yeni geçerli fiyat kaydı; tüm marka/mağazalar).
+ * Tüketim analizinde aylık maliyet tahmini için. Dönüşümü eksik ürünler atlanır.
+ */
+export async function latestTypeUnitPrices(
+  householdId: Types.ObjectId,
+  productTypeIds: Types.ObjectId[],
+  today = todayIstanbul(),
+): Promise<Map<string, { unitPriceMinor: number; date: string }>> {
+  const [products, types] = await Promise.all([
+    ProductModel.find({ householdId, productTypeId: { $in: productTypeIds } })
+      .select({ productTypeId: 1, packageQuantity: 1, packageUnit: 1, typeQuantity: 1 })
+      .lean<
+        {
+          _id: Types.ObjectId;
+          productTypeId: Types.ObjectId;
+          packageQuantity: number;
+          packageUnit: string;
+          typeQuantity: number | null;
+        }[]
+      >(),
+    ProductTypeModel.find({ householdId, _id: { $in: productTypeIds } })
+      .select({ unit: 1 })
+      .lean<{ _id: Types.ObjectId; unit: string }[]>(),
+  ]);
+  const unitOf = new Map(types.map((x) => [String(x._id), x.unit]));
+  const prices = await loadPrices(
+    householdId,
+    products.map((p) => p._id),
+  );
+  const groups = new Map<string, PriceLean[]>();
+  for (const r of prices) {
+    const key = `${r.productId}:${r.storeId}`;
+    groups.set(key, [...(groups.get(key) ?? []), r]);
+  }
+  const productById = new Map(products.map((p) => [String(p._id), p]));
+  const out = new Map<string, { unitPriceMinor: number; date: string }>();
+  for (const records of groups.values()) {
+    const p = productById.get(String(records[0]!.productId))!;
+    const typeId = String(p.productTypeId);
+    const inType = packageInTypeUnit({
+      packageQuantity: p.packageQuantity,
+      packageUnit: p.packageUnit,
+      typeUnit: unitOf.get(typeId) ?? "",
+      typeQuantity: p.typeQuantity,
+    });
+    if (!inType) continue;
+    const eff = effectivePrice(records, today)!;
+    const prev = out.get(typeId);
+    if (!prev || eff.record.date > prev.date)
+      out.set(typeId, {
+        unitPriceMinor: unitPrice(eff.record.priceMinor, inType),
+        date: eff.record.date,
+      });
+  }
+  return out;
+}
+
+// --- Yazma ---
+
+async function activeRefs(m: Membership, input: Pick<ProductPriceForm, "productId" | "storeId">) {
+  const [product, store] = await Promise.all([
+    ProductModel.exists({
+      _id: new Types.ObjectId(input.productId),
+      householdId: m.householdId,
+      archivedAt: null,
+    }),
+    StoreModel.exists({
+      _id: new Types.ObjectId(input.storeId),
+      householdId: m.householdId,
+      archivedAt: null,
+    }),
+  ]);
+  if (!product) return fail(t.validation.product, { productId: t.validation.product });
+  if (!store) return fail(t.validation.store, { storeId: t.validation.store });
+  return null;
+}
+
+/** Fiyat kaydı ekler. Gelecek tarihli fiyat girilemez. */
+export async function addProductPrice(
+  actorId: string,
+  householdId: string,
+  input: ProductPriceForm,
+  source: PriceSource = "manual",
+): Promise<ActionResult<{ id: string }>> {
+  const m = await resolveMembership(actorId, householdId, "member");
+  if (!m) return fail(tr.common.unauthorized);
+  if (input.date > todayIstanbul())
+    return fail(t.validation.futureDate, { date: t.validation.futureDate });
+  const bad = await activeRefs(m, input);
+  if (bad) return bad;
+  const doc = await ProductPriceModel.create({
+    householdId: m.householdId,
+    productId: new Types.ObjectId(input.productId),
+    storeId: new Types.ObjectId(input.storeId),
+    date: input.date,
+    priceMinor: input.priceMinor,
+    isPromo: input.isPromo,
+    promoUntil: input.promoUntil,
+    source,
+    note: input.note,
+    createdBy: new Types.ObjectId(actorId),
+  });
+  return ok({ id: String(doc._id) });
+}
+
+export async function deleteProductPrice(
+  actorId: string,
+  householdId: string,
+  priceId: string,
+): Promise<ActionResult> {
+  const m = await resolveMembership(actorId, householdId, "member");
+  if (!m) return fail(tr.common.unauthorized);
+  const id = toObjectId(priceId);
+  const row = id
+    ? await ProductPriceModel.findOne({
+        _id: id,
+        householdId: m.householdId,
+        deletedAt: null,
+      }).lean<PriceLean>()
+    : null;
+  if (!row) return fail(tr.common.notFound);
+  const actor = new Types.ObjectId(actorId);
+  await ProductPriceModel.updateOne({ _id: row._id }, { $set: { deletedAt: new Date() } });
+  await writeAudit({
+    action: "price.delete",
+    actorId: actor,
+    householdId: m.householdId,
+    targetType: "productPrice",
+    targetId: priceId,
+    diff: {
+      productId: String(row.productId),
+      storeId: String(row.storeId),
+      date: row.date,
+      priceMinor: row.priceMinor,
+    },
+  });
+  return ok(undefined);
+}
+
+export type { PriceProductOption };
diff --git a/src/features/stock/service.ts b/src/features/stock/service.ts
index 229227f..b31b546 100644
--- a/src/features/stock/service.ts
+++ b/src/features/stock/service.ts
@@ -12,6 +12,7 @@ import {
 } from "@/features/categories/tree";
 import { hasHouseholdRole } from "@/features/households/roles";
 import { resolveMembership, type Membership } from "@/features/households/service";
+import { latestTypeUnitPrices } from "@/features/prices/service";
 import { tr } from "@/i18n/tr";
 import { fail, ok, type ActionResult } from "@/lib/action-result";
 import { writeAudit } from "@/lib/audit";
@@ -24,6 +25,7 @@ import { StockCountModel } from "@/models/stock-count";
 import { StockMovementModel } from "@/models/stock-movement";
 import { todayIstanbul } from "@/shared/dates";
 import { shiftMonth } from "@/shared/budget";
+import { QUANTITY_SCALE } from "@/shared/quantity";
 import type {
   ProductTypeForm,
   StockCategoryForm,
@@ -1242,6 +1244,10 @@ export type StockAnalysisRow = {
   avgMonthlyWasted: number | null;
   /** Fire / (kullanım + fire), %. */
   wastePct: number | null;
+  /** Son bilinen birim fiyat (ürün tipi biriminde, kesirli kuruş) ve tarihi. */
+  unitPrice: { minor: number; date: string } | null;
+  /** Aylık ortalama maliyet tahmini: ortalama tüketim × son birim fiyat (kuruş). */
+  avgMonthlyCostMinor: number | null;
   /** Bu ay (bugüne kadar). */
   thisMonth: MonthUsage;
 };
@@ -1264,10 +1270,11 @@ export async function getStockAnalysis(
     shiftMonth(thisMonth, i - ANALYSIS_MONTHS),
   );
   const m = (await resolveMembership(userId, householdId, "viewer"))!;
-  const moves = await loadMoves(
-    m.householdId,
-    data.items.map((i) => new Types.ObjectId(i.id)),
-  );
+  const ids = data.items.map((i) => new Types.ObjectId(i.id));
+  const [moves, prices] = await Promise.all([
+    loadMoves(m.householdId, ids),
+    latestTypeUnitPrices(m.householdId, ids, data.today),
+  ]);
   const rows = data.items.map((item): StockAnalysisRow => {
     const list = moves.get(item.id) ?? [];
     const [usage, current] = [monthlyUsage(list, months), monthlyUsage(list, [thisMonth])[0]!];
@@ -1277,6 +1284,8 @@ export async function getStockAnalysis(
     const sum = (k: "used" | "wasted") => full.reduce((s, u) => s + u[k], 0);
     const used = sum("used");
     const wasted = sum("wasted");
+    const price = prices.get(item.id) ?? null;
+    const avgUsed = full.length ? used / full.length : null;
     return {
       id: item.id,
       name: item.name,
@@ -1287,6 +1296,11 @@ export async function getStockAnalysis(
       avgMonthlyUsed: full.length ? roundForDisplay(used / full.length) : null,
       avgMonthlyWasted: full.length ? roundForDisplay(wasted / full.length) : null,
       wastePct: used + wasted > 0 ? Math.round((wasted * 100) / (used + wasted)) : null,
+      unitPrice: price ? { minor: price.unitPriceMinor, date: price.date } : null,
+      avgMonthlyCostMinor:
+        price && avgUsed !== null
+          ? Math.round((avgUsed * price.unitPriceMinor) / QUANTITY_SCALE)
+          : null,
       thisMonth: current,
     };
   });
diff --git a/src/i18n/tr.ts b/src/i18n/tr.ts
index 6e10a0b..c4def65 100644
--- a/src/i18n/tr.ts
+++ b/src/i18n/tr.ts
@@ -981,7 +981,11 @@ export const tr = {
     analysis: {
       title: "Tüketim analizi",
       description:
-        "Ürün tipi başına aylık tüketim ve fire. Tüketim: girilen tüketimler ve sayımda çıkan eksikler. Maliyet, ürün fiyatları (Faz 12) gelince eklenecek.",
+        "Ürün tipi başına aylık tüketim, fire ve tahmini maliyet. Tüketim: girilen tüketimler ve sayımda çıkan eksikler. Maliyet: aylık ortalama tüketim × son bilinen birim fiyat.",
+      avgCost: "Aylık ort. maliyet",
+      costHint: (price: string, date: string) => `Son birim fiyat ${price} (${date})`,
+      noPrice: "Fiyat yok",
+      totalCost: (total: string) => `Fiyatı bilinen ürünlerde aylık tahmini maliyet: ${total}`,
       back: "Ev stoğuna dön",
       product: "Ürün tipi",
       avgUsed: "Aylık ort. tüketim",
@@ -1348,6 +1352,65 @@ export const tr = {
       archived: "Ürün arşivli.",
     },
   },
+  productPrices: {
+    add: "Fiyat gir",
+    addTitle: "Fiyat gir",
+    comparisonTitle: "Birim fiyat karşılaştırması",
+    comparisonDescription: (unit: string) =>
+      `Marka ve mağazaların son bilinen fiyatları, 1 ${unit} başına sıralı. Süresi biten kampanyada önceki normal fiyat kullanılır.`,
+    noPrices: "Henüz fiyat girilmedi.",
+    noProducts: "Fiyat girmek için önce bir ürün (marka/paket) ekleyin.",
+    cheapest: "En uygun",
+    diff: (pct: number) => `%${pct} pahalı`,
+    perUnit: "Birim fiyat",
+    packagePrice: "Paket fiyatı",
+    store: "Mağaza",
+    product: "Ürün",
+    date: "Tarih",
+    promo: "Kampanya",
+    promoUntil: (date: string) => `${date} tarihine kadar`,
+    promoEnded: "Kampanya bitti",
+    fellBack: "Kampanya bitti, normal fiyat",
+    stale: (days: number) => `${days} gün önce`,
+    staleHint: "90 günden eski fiyat; güncel olmayabilir.",
+    noConversion: "Dönüşüm yok",
+    sources: { manual: "Elle", receipt: "Fiş", provider: "Sağlayıcı" } as Record<string, string>,
+    detail: {
+      back: "Ürün kataloğu",
+      typeLink: (name: string) => `Ürün tipi: ${name}`,
+      currentTitle: "Mağazalardaki fiyatlar",
+      currentDescription: "Her mağazadaki geçerli (son) fiyat; birim fiyata göre sıralı.",
+      chartTitle: "Fiyat geçmişi",
+      chartDescription: "Mağaza başına paket fiyatı; fiyat yeni kayda kadar geçerli sayılır.",
+      chartLabel: (name: string) => `${name}: mağaza başına fiyat geçmişi`,
+      historyTitle: "Fiyat kayıtları",
+      deletePrice: "Fiyat kaydını sil",
+      deleteTitle: "Fiyat kaydı silinsin mi?",
+      deleteDescription: "Kayıt fiyat geçmişinden ve karşılaştırmadan çıkarılır.",
+      images: "Görseller",
+      barcode: "Barkod",
+      package: "Paket",
+    },
+    fields: {
+      product: "Ürün",
+      store: "Mağaza",
+      date: "Tarih",
+      price: "Paket fiyatı (₺)",
+      isPromo: "Kampanya / indirim",
+      promoUntil: "Kampanya bitişi",
+      promoUntilHint: "İsteğe bağlı. Bitince karşılaştırmada önceki normal fiyat kullanılır.",
+      note: "Not",
+      unitPreview: (value: string) => `Birim fiyat: ${value}`,
+    },
+    toast: { saved: "Fiyat kaydedildi.", deleted: "Fiyat kaydı silindi." },
+    validation: {
+      product: "Aktif bir ürün seçin",
+      store: "Aktif bir mağaza seçin",
+      price: "Geçerli bir fiyat girin (ör. 89,90)",
+      promoUntil: "Kampanya bitişi fiyat tarihinden önce olamaz",
+      futureDate: "Gelecek tarihli fiyat girilemez",
+    },
+  },
   prices: {
     title: "Fiyat tablosu",
     description:
diff --git a/src/models/audit-log.ts b/src/models/audit-log.ts
index 1abbc93..f7f3336 100644
--- a/src/models/audit-log.ts
+++ b/src/models/audit-log.ts
@@ -44,6 +44,7 @@ export const AUDIT_ACTIONS = [
   "store.unarchive",
   "product.archive",
   "product.unarchive",
+  "price.delete",
 ] as const;
 export type AuditAction = (typeof AUDIT_ACTIONS)[number];
 
diff --git a/src/models/product-price.ts b/src/models/product-price.ts
new file mode 100644
index 0000000..8eb9474
--- /dev/null
+++ b/src/models/product-price.ts
@@ -0,0 +1,38 @@
+import { model, models, Schema, type InferSchemaType, type Model } from "mongoose";
+
+/**
+ * Ürün fiyat kaydı (Bölüm 6.11): ürün × mağaza × tarih × paket fiyatı (kuruş). Kampanya işareti
+ * ve geçerlilik sonu; kaynak `manual` | `receipt` | `provider:<ad>`. Hane bazlı. Birim fiyat
+ * okuma sırasında ürünün dönüşümüyle hesaplanır (saklanmaz).
+ */
+const productPriceSchema = new Schema(
+  {
+    householdId: { type: Schema.Types.ObjectId, required: true },
+    productId: { type: Schema.Types.ObjectId, required: true },
+    storeId: { type: Schema.Types.ObjectId, required: true },
+    /** "YYYY-MM-DD" (İstanbul). */
+    date: { type: String, required: true },
+    priceMinor: { type: Number, required: true, min: 1 },
+    isPromo: { type: Boolean, default: false },
+    promoUntil: { type: String, default: null },
+    source: { type: String, required: true, match: /^(manual|receipt|provider:[a-z0-9-]{1,40})$/ },
+    note: { type: String, default: "", maxlength: 300 },
+    deletedAt: { type: Date, default: null },
+    seedRef: { type: String, default: null },
+    createdBy: { type: Schema.Types.ObjectId, required: true },
+  },
+  { timestamps: true, collection: "productPrices" },
+);
+
+productPriceSchema.index({ householdId: 1, productId: 1, deletedAt: 1, date: 1, createdAt: 1 });
+productPriceSchema.index({ householdId: 1, storeId: 1, date: -1 });
+productPriceSchema.index(
+  { householdId: 1, seedRef: 1 },
+  { unique: true, partialFilterExpression: { seedRef: { $type: "string" } } },
+);
+
+export type ProductPrice = InferSchemaType<typeof productPriceSchema>;
+
+export const ProductPriceModel: Model<ProductPrice> =
+  (models.ProductPrice as Model<ProductPrice> | undefined) ??
+  model<ProductPrice>("ProductPrice", productPriceSchema);
diff --git a/src/shared/prices.test.ts b/src/shared/prices.test.ts
new file mode 100644
index 0000000..bcc9beb
--- /dev/null
+++ b/src/shared/prices.test.ts
@@ -0,0 +1,92 @@
+import { describe, expect, it } from "vitest";
+import {
+  effectivePrice,
+  formatUnitPrice,
+  PRICE_SOURCE_PATTERN,
+  rankOffers,
+  seriesSlot,
+  unitPrice,
+  unitPriceBase,
+} from "./prices";
+
+const r = (
+  date: string,
+  priceMinor: number,
+  isPromo = false,
+  promoUntil: string | null = null,
+) => ({
+  date,
+  priceMinor,
+  isPromo,
+  promoUntil,
+});
+
+describe("birim fiyat", () => {
+  it("paket fiyatı / ürün tipi birimindeki miktar; yuvarlama yalnızca gösterimde", () => {
+    // Ariel 5 kg = 33 yıkama, 519,90 TL → 15,754… TL/yıkama.
+    const u = unitPrice(519_90, 33_000);
+    expect(u).toBeCloseTo(1575.4545, 3);
+    expect(formatUnitPrice(u, "yıkama")).toMatch(/15,75\/yıkama$/);
+    // 500 g beyaz peynir 210 TL, ürün tipi g olsaydı: 0,42 TL/g → 420 TL/kg.
+    expect(formatUnitPrice(unitPrice(210_00, 500_000), "g")).toMatch(/420,00\/kg$/);
+    expect(unitPriceBase("ml")).toEqual({ unit: "lt", factor: 1000 });
+    expect(unitPriceBase("adet")).toEqual({ unit: "adet", factor: 1 });
+  });
+
+  it("kaynak biçimi", () => {
+    expect(
+      ["manual", "receipt", "provider:marketfiyati"].every((s) => PRICE_SOURCE_PATTERN.test(s)),
+    ).toBe(true);
+    expect(PRICE_SOURCE_PATTERN.test("provider:")).toBe(false);
+    expect(PRICE_SOURCE_PATTERN.test("scrape")).toBe(false);
+  });
+});
+
+describe("geçerli fiyat", () => {
+  const today = "2026-11-06";
+
+  it("son kayıt; süresi biten kampanyada önceki normal fiyata dönülür", () => {
+    expect(effectivePrice([], today)).toBeNull();
+    const normal = effectivePrice([r("2026-10-01", 100_00), r("2026-11-01", 110_00)], today)!;
+    expect(normal).toMatchObject({ record: { priceMinor: 110_00 }, fellBack: false, ageDays: 5 });
+    const ended = effectivePrice(
+      [r("2026-10-01", 100_00), r("2026-10-20", 80_00, true, "2026-10-31")],
+      today,
+    )!;
+    expect(ended).toMatchObject({
+      record: { priceMinor: 100_00 },
+      fellBack: true,
+      promoEnded: false,
+    });
+    const active = effectivePrice(
+      [r("2026-10-01", 100_00), r("2026-11-02", 80_00, true, "2026-11-10")],
+      today,
+    )!;
+    expect(active).toMatchObject({ record: { priceMinor: 80_00 }, fellBack: false });
+    // Dönülecek normal fiyat yoksa kampanya fiyatı işaretle.
+    const only = effectivePrice([r("2026-10-20", 80_00, true, "2026-10-31")], today)!;
+    expect(only).toMatchObject({ fellBack: false, promoEnded: true });
+    expect(effectivePrice([r("2026-07-01", 1)], today)!.stale).toBe(true);
+    expect(effectivePrice([r("2026-09-01", 1)], today)!.stale).toBe(false);
+  });
+});
+
+describe("sıralama", () => {
+  it("birim fiyata göre artan, eşitler en uygun, hesaplanamayan sonda", () => {
+    const ranked = rankOffers([
+      { id: "a", unitPriceMinor: 1_500 },
+      { id: "b", unitPriceMinor: null },
+      { id: "c", unitPriceMinor: 1_200 },
+      { id: "d", unitPriceMinor: 1_200 },
+      { id: "e", unitPriceMinor: 1_800 },
+    ]);
+    expect(ranked.map((o) => [o.id, o.rank, o.cheapest, o.diffPct])).toEqual([
+      ["c", 1, true, 0],
+      ["d", 2, true, 0],
+      ["a", 3, false, 25],
+      ["e", 4, false, 50],
+      ["b", null, false, null],
+    ]);
+    expect([seriesSlot(0), seriesSlot(7), seriesSlot(8)]).toEqual([1, 8, 1]);
+  });
+});
diff --git a/src/shared/prices.ts b/src/shared/prices.ts
new file mode 100644
index 0000000..5ccf51f
--- /dev/null
+++ b/src/shared/prices.ts
@@ -0,0 +1,124 @@
+import { daysBetween } from "./budget";
+import { formatMoney } from "./format";
+import { QUANTITY_SCALE } from "./quantity";
+
+/**
+ * Ürün fiyatı ve birim fiyat motoru (Bölüm 6.11). Saf fonksiyonlar.
+ *
+ * Fiyat paket fiyatıdır (kuruş). Birim fiyat, ürün tipinin biriminde 1 birimin fiyatıdır:
+ *   birim fiyat = paket fiyatı × 1000 / (paketin ürün tipi birimindeki miktarı, binde bir)
+ * Kesirli kuruş olarak tutulur; yuvarlama yalnızca gösterimde. Gösterimde g → kg, ml → lt.
+ */
+
+export const PRICE_SOURCE_PATTERN = /^(manual|receipt|provider:[a-z0-9-]{1,40})$/;
+export type PriceSource = "manual" | "receipt" | `provider:${string}`;
+
+/** Bu kadar günden eski fiyat "eski" sayılır. */
+export const PRICE_STALE_DAYS = 90;
+
+export function unitPrice(priceMinor: number, packageInTypeUnit: number): number {
+  return (priceMinor * QUANTITY_SCALE) / packageInTypeUnit;
+}
+
+/** Gösterim birimi: küçük birimler büyüğe (g → kg, ml → lt). */
+export function unitPriceBase(typeUnit: string): { unit: string; factor: number } {
+  if (typeUnit === "g") return { unit: "kg", factor: 1000 };
+  if (typeUnit === "ml") return { unit: "lt", factor: 1000 };
+  return { unit: typeUnit, factor: 1 };
+}
+
+/** 4250 kuruş/kg → "₺42,50/kg"; g biriminde 4,25 kuruş/g → "₺42,50/kg". */
+export function formatUnitPrice(unitPriceMinor: number, typeUnit: string): string {
+  const base = unitPriceBase(typeUnit);
+  return `${formatMoney(Math.round(unitPriceMinor * base.factor))}/${base.unit}`;
+}
+
+export type PriceRecordLike = {
+  date: string;
+  priceMinor: number;
+  isPromo: boolean;
+  /** Kampanya geçerlilik sonu (dahil); yoksa süresiz. */
+  promoUntil: string | null;
+};
+
+export const promoEnded = (r: PriceRecordLike, today: string) =>
+  r.isPromo && r.promoUntil !== null && r.promoUntil < today;
+
+export type EffectivePrice<T> = {
+  record: T;
+  /** Son kayıt süresi biten kampanyaydı; önceki normal fiyata dönüldü. */
+  fellBack: boolean;
+  /** Geçerli fiyat süresi biten kampanya (dönülecek normal fiyat yok). */
+  promoEnded: boolean;
+  ageDays: number;
+  stale: boolean;
+};
+
+/**
+ * Geçerli fiyat: tarih (ve giriş) sırasındaki son kayıt. Son kayıt süresi biten kampanyaysa,
+ * ondan önceki son kampanyasız (veya hâlâ geçerli kampanyalı) kayda dönülür; yoksa kampanya
+ * fiyatı işaretle kullanılır. `records` eskiden yeniye sıralı olmalı.
+ */
+export function effectivePrice<T extends PriceRecordLike>(
+  records: readonly T[],
+  today: string,
+): EffectivePrice<T> | null {
+  const latest = records.at(-1);
+  if (!latest) return null;
+  let record = latest;
+  let fellBack = false;
+  if (promoEnded(latest, today)) {
+    const prev = [...records].reverse().find((r) => !promoEnded(r, today));
+    if (prev) {
+      record = prev;
+      fellBack = true;
+    }
+  }
+  const ageDays = record.date <= today ? daysBetween(record.date, today) - 1 : 0;
+  return {
+    record,
+    fellBack,
+    promoEnded: promoEnded(record, today),
+    ageDays,
+    stale: ageDays > PRICE_STALE_DAYS,
+  };
+}
+
+export type Offer = { unitPriceMinor: number | null };
+
+export type RankedOffer<T> = T & {
+  rank: number | null;
+  cheapest: boolean;
+  /** En uygundan yüzde fark (tamsayı); en uygunda 0. */
+  diffPct: number | null;
+};
+
+/**
+ * Birim fiyata göre sıralar (artan); birim fiyatı hesaplanamayanlar (dönüşüm eksik) sonda.
+ * En düşük birim fiyatlı tüm teklifler (eşitlik dahil) "en uygun".
+ */
+export function rankOffers<T extends Offer>(offers: readonly T[]): RankedOffer<T>[] {
+  const priced = offers.filter((o) => o.unitPriceMinor !== null);
+  const min = priced.length ? Math.min(...priced.map((o) => o.unitPriceMinor!)) : null;
+  const sorted = [...offers].sort((a, b) => {
+    if (a.unitPriceMinor === null || b.unitPriceMinor === null)
+      return a.unitPriceMinor === null ? (b.unitPriceMinor === null ? 0 : 1) : -1;
+    return a.unitPriceMinor - b.unitPriceMinor;
+  });
+  let rank = 0;
+  return sorted.map((o) => {
+    if (o.unitPriceMinor === null || min === null)
+      return { ...o, rank: null, cheapest: false, diffPct: null };
+    rank++;
+    return {
+      ...o,
+      rank,
+      cheapest: Math.abs(o.unitPriceMinor - min) < 1e-9,
+      diffPct: min > 0 ? Math.round(((o.unitPriceMinor - min) * 100) / min) : 0,
+    };
+  });
+}
+
+/** Grafik/legend için mağaza renk yuvası (1–8): mağazanın hanedeki ekleniş sırasına göre sabit. */
+export const SERIES_SLOTS = 8;
+export const seriesSlot = (storeIndex: number) => (storeIndex % SERIES_SLOTS) + 1;
diff --git a/src/shared/schemas/product-price.ts b/src/shared/schemas/product-price.ts
new file mode 100644
index 0000000..0cc2a26
--- /dev/null
+++ b/src/shared/schemas/product-price.ts
@@ -0,0 +1,41 @@
+import { z } from "zod";
+import { tr } from "../../i18n/tr";
+import { parseMoney } from "../money";
+
+const v = tr.validation;
+const s = tr.productPrices.validation;
+const ymd = z.string().regex(/^\d{4}-\d{2}-\d{2}$/, v.date);
+const id = (message: string) => z.string().regex(/^[a-f0-9]{24}$/i, message);
+
+/** Elle fiyat girişi (kaynak: manual). Paket fiyatı TL; kampanyada geçerlilik sonu isteğe bağlı. */
+export const productPriceFormSchema = z
+  .object({
+    productId: id(s.product),
+    storeId: id(s.store),
+    date: ymd,
+    price: z
+      .string()
+      .trim()
+      .transform((x, ctx) => {
+        const minor = parseMoney(x);
+        if (minor === null || minor <= 0) {
+          ctx.addIssue({ code: "custom", message: s.price });
+          return z.NEVER;
+        }
+        return minor;
+      }),
+    isPromo: z.boolean(),
+    promoUntil: z.preprocess((x) => (x === "" || x === undefined ? null : x), ymd.nullable()),
+    note: z.string().trim().max(300).default(""),
+  })
+  .superRefine((x, ctx) => {
+    if (x.isPromo && x.promoUntil && x.promoUntil < x.date)
+      ctx.addIssue({ code: "custom", path: ["promoUntil"], message: s.promoUntil });
+  })
+  .transform(({ price, ...x }) => ({
+    ...x,
+    priceMinor: price,
+    promoUntil: x.isPromo ? x.promoUntil : null,
+  }));
+export type ProductPriceFormInput = z.input<typeof productPriceFormSchema>;
+export type ProductPriceForm = z.output<typeof productPriceFormSchema>;