This check digit calculator works out the GS1 Mod 10 check digit for GTIN-8 (EAN-8), GTIN-12 (UPC-A), GTIN-13 (EAN-13), GTIN-14, GLN, GSIN, SSCC and GSRN numbers, or verifies a full number you already have. Paste one number or a list of up to 1,000, one per line; spaces and dashes are ignored.
How to use the check digit calculator
- Choose Calculate (number without its last digit) or Verify (full number).
- Paste one number or a list, one per line.
- Read the result for each line and copy the full numbers.
What is a check digit?
A check digit is the last digit of a GS1 identification number, such as a UPC or EAN. It is calculated from all the digits before it, so a scanner or a computer can catch a number that was mistyped or misread.
How to calculate a GS1 check digit
- Write the number without its check digit.
- Starting from the right, multiply the digits by 3, 1, 3, 1 and so on.
- Add all the results.
- The check digit is the amount needed to reach the next multiple of 10. If the sum is already a multiple of 10, the check digit is 0.
Example from GS1 UK: for the number 501234567421, the weighted sum is 74, so the check digit is 6 and the full GTIN-13 is 5012345674216.
Which numbers use the GS1 check digit?
| Number | Digits | Where it appears |
|---|---|---|
| GTIN-8 | 8 | EAN-8 barcode on small packs |
| GTIN-12 | 12 | UPC-A barcode in the United States and Canada |
| GTIN-13 | 13 | EAN-13 barcode in most other countries |
| GLN (Global Location Number) | 13 | Identifies a company or location |
| GTIN-14 | 14 | ITF-14 barcode on cartons and cases |
| GSIN (Global Shipment Identification Number) | 17 | Identifies a shipment |
| SSCC (Serial Shipping Container Code) | 18 | GS1-128 label on pallets and parcels |
| GSRN (Global Service Relation Number) | 18 | Identifies a service relationship |
All of them use the same Mod 10 rule, so the calculator picks the key by the number of digits you enter.
UPC check digit calculator
For a UPC, enter the first 11 digits. Example: for 03600029145, the weighted sum is 58, so the check digit is 2 and the full UPC-A is 036000291452. To turn the full number into a barcode, use the UPC barcode generator.
Convert UPC, EAN and ISBN numbers
Choose Convert to change a list of numbers from one GS1 form to another. The check digit is recalculated for every result.
| Conversion | Example | Result |
|---|---|---|
| UPC-A → EAN-13 | 036000291452 | 0036000291452 |
| EAN-13 → UPC-A (starts with 0) | 0036000291452 | 036000291452 |
| UPC-E → UPC-A | 01234565 | 012345000065 |
| UPC-A → UPC-E (when the zeros allow it) | 012345000065 | 01234565 |
| ISBN-10 → ISBN-13 | 0-306-40615-2 | 9780306406157 |
Only some UPC-A numbers can be shortened to UPC-E, because UPC-E drops a run of zeros from the number. The calculator tells you when a number cannot be shortened.
What a correct check digit does not prove
A correct check digit means the number is typed correctly. It does not mean the number is registered, or that it belongs to the company using it. Ownership of a GTIN is checked in the GS1 registry.
Is it private?
Yes. The check digits are calculated in your browser. The numbers you paste are not sent to our server.
Tips for check digits
- Keep leading zeros; a UPC that starts with 0 is still 12 digits.
- Verify every number before you print packaging or labels.
- Paste a whole list to find typing errors in one pass.
- Use Verify for numbers you receive from suppliers or customers.
- Copy the full numbers from the result rather than retyping them.
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Frequently asked questions
Is the check digit the same for UPC and EAN?
Yes. UPC, EAN, GTIN-14, GLN and SSCC all use the same GS1 Mod 10 rule.
Why is my UPC check digit wrong?
One of the first 11 digits was mistyped, the digits were swapped, or a leading zero was dropped. Re-enter the number and compare.
Can I check many numbers at once?
Yes. Paste up to 1,000 numbers, one per line.
Does it work for ISBN-10?
No. ISBN-10 uses a different rule (Mod 11). A 13-digit ISBN uses the GS1 rule and works here.
Does a valid check digit mean the barcode is registered?
No. It only proves the digits are consistent. Registration is checked with GS1.