diff --git a/src/food-market.web/src/lib/barcode.ts b/src/food-market.web/src/lib/barcode.ts
new file mode 100644
index 0000000..37767ad
--- /dev/null
+++ b/src/food-market.web/src/lib/barcode.ts
@@ -0,0 +1,21 @@
+// EAN-13 утилиты.
+//
+// Внутренние штрихкоды магазина начинаются с "2" — это зарезервированный
+// префикс для in-store use, он не пересекается с GTIN реальных товаров
+// от производителей.
+
+function ean13Checksum(first12: string): number {
+  let sum = 0
+  for (let i = 0; i < 12; i++) {
+    const d = first12.charCodeAt(i) - 48
+    sum += i % 2 === 0 ? d : d * 3
+  }
+  return (10 - (sum % 10)) % 10
+}
+
+/** Сгенерировать внутренний EAN-13 с префиксом "2" и случайной серединой. */
+export function generateEan13InternalPrefix2(): string {
+  let body = '2'
+  for (let i = 0; i < 11; i++) body += Math.floor(Math.random() * 10).toString()
+  return body + ean13Checksum(body).toString()
+}
diff --git a/src/food-market.web/src/pages/ProductEditPage.tsx b/src/food-market.web/src/pages/ProductEditPage.tsx
index 7695df9..7e072e8 100644
--- a/src/food-market.web/src/pages/ProductEditPage.tsx
+++ b/src/food-market.web/src/pages/ProductEditPage.tsx
@@ -11,6 +11,7 @@ import {
 import { useOrgSettings } from '@/lib/useOrgSettings'
 import { BarcodeType, Packaging, type Product } from '@/lib/types'
 import { ProductImageGallery } from '@/components/ProductImageGallery'
+import { generateEan13InternalPrefix2 } from '@/lib/barcode'
 
 interface PriceRow { id?: string; priceTypeId: string; amount: number; currencyId: string }
 interface BarcodeRow { id?: string; code: string; type: BarcodeType; isPrimary: boolean }
@@ -167,7 +168,7 @@ export function ProductEditPage() {
     setForm({ ...form, prices: form.prices.map((p, ix) => ix === i ? { ...p, ...patch } : p) })
 
   const addBarcode = () => setForm({ ...form, barcodes: [...form.barcodes, {
-    code: '', type: BarcodeType.Ean13, isPrimary: form.barcodes.length === 0,
+    code: generateEan13InternalPrefix2(), type: BarcodeType.Ean13, isPrimary: form.barcodes.length === 0,
   }] })
   const removeBarcode = (i: number) =>
     setForm({ ...form, barcodes: form.barcodes.filter((_, ix) => ix !== i) })