GTIN check digit calculator
Calculate or check the last digit of a GTIN-8, GTIN-12 (UPC-A), GTIN-13 (EAN-13) or GTIN-14. Select the type. Enter the code without its last digit to get the check digit, or enter the full code to check it. Scanners and stock systems recalculate this digit to catch a wrong digit in the number.
How does it work?
All GTIN lengths use the same GS1 modulo 10 method:
- Take the data digits: the code without its last digit.
- Start at the rightmost data digit. Multiply it by 3, the next digit to the left by 1, the next by 3, and so on.
- Add all the results.
- Find the amount that brings the sum up to the next multiple of 10. That amount is the check digit. If the sum is already a multiple of 10, the check digit is 0.
Example for the EAN-13 data digits 590123412345: from the right, the weighted sum is 83. The next multiple of 10 is 90, so the check digit is 7 and the full code is 5901234123457.
Many manuals and API references show example codes with a wrong last digit. Our study invalid example barcodes in public documentation lists the most copied ones and their correct form.
What do barcode numbers mean?
The numbers in a barcode describe the product or item it represents. A typical barcode starts with a GS1 prefix. The prefix shows which GS1 member organisation issued the number. It does not show where the product was made. It also includes a manufacturer code, which identifies the company that produced the item. The product code follows and identifies the product within that manufacturer's range. A check digit is often included to catch errors. When scanned, these numbers are used for inventory management, pricing and tracking through the supply chain, and for logistics, sales and stock management.
Frequently asked questions
Is the check digit rule the same for UPC, EAN and GTIN-14?
Yes. GTIN-8, GTIN-12 (UPC-A), GTIN-13 (EAN-13) and GTIN-14 use the same GS1 modulo 10 rule. The weights 3 and 1 alternate from the rightmost data digit. A UPC-A keeps its check digit when you add leading zeros to make a GTIN-13 or GTIN-14, because a zero adds nothing to the sum.
How do I calculate a GTIN-14 check digit?
Select GTIN-14 and enter the first 13 digits. The calculator shows the 14th digit and the full GTIN-14. To check a printed GTIN-14, enter all 14 digits.
Why does the calculator give a different digit than the box?
Check the selected type first. With GTIN-13 selected, 12 digits are read as the data digits of an EAN-13, not as a full UPC-A. If the type is correct, a digit was probably typed or read wrong.
Can I use it for a UPC-E code?
Not directly. A UPC-E is a short form of a UPC-A, and its check digit comes from the expanded 12-digit UPC-A. Expand the UPC-E first, then select GTIN-12.
Does a correct check digit prove that a barcode is real?
No. A correct check digit shows that the number is well formed. It does not show that a company owns the number or which product it belongs to. The barcode validation tool checks the full structure, and the sneaker barcode lookup finds the product.
Related tools: the UPC check digit calculator, the barcode validation tool and the GTIN converter.
Which product is this barcode?
Checking a sneaker or streetwear barcode? Look it up to see the product it belongs to. Free, no account.
Have manufacturer style codes in a CSV? Enrich your catalogue in bulk. For a recurring integration, the barcode lookup API returns product, size and images for each code, with a 7-day free trial. The sneaker price API adds resale prices for the size of each barcode.
Learn more
How to calculate a UPC/EAN check digit by hand
Compute the modulo-10 check digit for any UPC-A or EAN-13 with a pen, paper, and one small rule.
EAN-13 format explained: structure & prefixes
An EAN-13 barcode is a 13-digit GTIN-13 built from a GS1 prefix, a company prefix, an item reference and a check digit.
Why your barcode check digit does not match: 7 causes
The seven reasons a UPC or EAN check digit fails validation, and how to fix each one.
How to validate a barcode: UPC, EAN & GTIN
A practical guide to checking that a UPC, EAN, or GTIN is well formed before you trust it.