# GTIN Check Digit Calculator & Validator

> Check whether a UPC, EAN or GTIN-14 is valid, calculate the missing check digit, see which GS1 organisation issued the prefix, and bulk-validate a whole product list.

- Source: https://plugstack.dev/tools/gtin-check-digit-calculator/
- Published by: PlugStack
- Last updated: 2026-09-24

## GTIN formats

 

| Format | Digits | Used for |
| --- | --- | --- |
| GTIN-8 (EAN-8) | 8 | Very small retail packages |
| GTIN-12 (UPC-A) | 12 | Retail products, mainly US and Canada |
| GTIN-13 (EAN-13) | 13 | Retail products worldwide, books (ISBN-13) |
| GTIN-14 | 14 | Cases and cartons (printed as ITF-14) |

 

The last digit of every GTIN is a check digit calculated from the others. It catches typos: a single wrong digit or two swapped neighbouring digits almost always produce a different check digit.

 

## The check digit algorithm (GS1 mod 10)

 
1. Take the number without its last digit.
2. From the right, multiply the digits by 3, 1, 3, 1…
3. Add the results.
4. Check digit = (10 − (sum mod 10)) mod 10.

 

**Example:** for the UPC body 03600029145 the weighted sum is 58, so the check digit is 2: **036000291452**.

 

## Before you upload GTINs

 

Marketplaces and Google Merchant Center validate GTINs automatically, and a bad one can get a product disapproved. Paste your list into *Bulk validate* to find wrong check digits and bad lengths, and download the corrected CSV. In WooCommerce the number goes in the product’s *GTIN, UPC, EAN or ISBN* field under Inventory.

 

Need the barcode image? Use the [barcode generator](https://plugstack.dev/tools/barcode-generator/) — EAN-13 or UPC-A for retail units, ITF-14 for cartons.

 

## Restricted and special prefixes

 
- **2xx (EAN) and 02/04 (UPC)** — restricted circulation: in-store codes for weighed or price-embedded items. Not valid for marketplaces.
- **978 / 979** — books (ISBN). **977** — periodicals (ISSN).
- **05, 99** — coupons.

## FAQ
### How is a GTIN check digit calculated?
Starting from the right of the number without its check digit, multiply the digits alternately by 3 and 1, add them up, and subtract the total from the next multiple of 10. For 400638133393 the weighted sum is 89, so the check digit is 1 and the full EAN-13 is 4006381333931.

### What is the difference between UPC, EAN and GTIN?
GTIN is the umbrella term. A UPC-A is a 12-digit GTIN (GTIN-12), an EAN-13 is a 13-digit GTIN, EAN-8 is GTIN-8, and GTIN-14 identifies cases and cartons. Any of them can be padded with leading zeros to 14 digits without changing its meaning.

### Does a valid check digit mean the GTIN is real?
No. A correct check digit only proves the number is well-formed. Whether it is assigned to your product can only be confirmed in GS1’s registry (Verified by GS1) or by the brand owner.

### Why does Google Merchant Center reject my GTIN?
Common reasons: a wrong check digit, a restricted in-store prefix (starting with 2, or 02/04 for UPC), a GTIN reused across different products, or a number that does not match the brand in GS1’s data. This tool catches the first two.

### Does the prefix show the country of origin?
No. The first digits show which national GS1 organisation issued the company prefix, not where the product was made.