GTIN Check Digit Calculator
Calculate a GTIN check digit and convert between UPC, EAN and GTIN-14
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GTIN check digit calculator
Work out the last digit of a GTIN-8, UPC-A, EAN-13 or GTIN-14, see the calculation step by step, and convert between formats.
7 digits for GTIN-8, 11 for UPC-A, 12 for EAN-13, 13 for GTIN-14.
A check digit only proves the number is well formed. It does not prove the number was issued to you. Only use GTINs from GS1 or your brand owner, and never make one up for a feed.
What this tool delivers
The last digit of a GTIN, UPC or EAN is a check digit that catches typing and scanning mistakes. This calculator works out the check digit for a code, shows the arithmetic step by step, verifies a full code, and converts between UPC-A, EAN-13 and GTIN-14. It is a quick way to understand why a code fails validation in a marketplace or in Merchant Center.
How it works
- 1
Enter the code
Give the code without its last digit to calculate it, or the full code to verify it. Spaces and hyphens are ignored.
- 2
See the working
Each digit is multiplied by 3 or 1 from the right, the products are added, and the check digit brings the total up to the next multiple of 10.
- 3
Convert if you need to
UPC-A becomes EAN-13 by adding a leading zero, and any item can be given a GTIN-14 packaging indicator with a new check digit.
Read the guide
The maths, worked examples and the conversion rules explained.
How GTIN check digits workUse it with
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Frequently Asked Questions
How is a GTIN check digit calculated?
Multiply the digits by 3 and 1 alternately, starting with 3 at the digit next to the check digit and moving left. Add the results. The check digit is the amount needed to reach the next multiple of 10.
Does a valid check digit mean the GTIN is real?
No. It only proves the number is well formed. A GTIN is only genuine if GS1 issued it to the brand owner. Never make up a GTIN for a feed.
How do I convert a UPC-A to an EAN-13?
Add a zero at the front. The check digit stays the same, because a leading zero does not change the weighted sum.
What is a GTIN-14?
A 14-digit code used for cases or packs. It is an indicator digit from 1 to 8, then the first 12 digits of the item's code, then a newly calculated check digit.
Why do my GTINs lose leading zeros?
Spreadsheets treat codes as numbers and drop leading zeros. Format the column as text before importing or exporting.
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