Check digit calculator
Work out the last digit of an EAN-13, UPC-A, EAN-8 or ITF-14 barcode number, or check that a whole number is valid. It shows the working, too.
- Free, no sign-up
- EAN, UPC and GTIN
- Shows the working
- Made in your browser
Just need the barcode? The barcode generator adds the check digit for you. Need an Android sales app for taking orders on the road or at trade shows? See Selenic Orders.
Enter the first 12 digits to work out the check digit, or all 13 to check a number. Spaces and hyphens are ignored.
Check digit
7
Full number: 5901234123457
Show the working
| Digit | 5 | 9 | 0 | 1 | 2 | 3 | 4 | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| × weight | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 |
| = | 5 | 27 | 0 | 3 | 2 | 9 | 4 | 3 | 2 | 9 | 4 | 15 |
Total 83. The next multiple of 10 is 90, so the check digit is 90 − 83 = 7.
How the check digit is worked out
EAN, UPC and ITF-14 numbers all use the same method, known as GS1 mod 10:
- Take the number without its last digit.
- Starting from the right, multiply the digits by 3, 1, 3, 1 and so on.
- Add up the results.
- The check digit is whatever you need to add to reach the next multiple of 10. If the total is already a multiple of 10, it’s 0.
For example, for 590123412345 the total is 83. The next multiple of 10 is 90, so the check digit is 7 and the full EAN-13 is 5901234123457.
Why barcodes have one
A single misread digit, or two digits swapped by hand, almost always changes the check digit. Scanners and tills recalculate it on every scan, so a damaged or mistyped number is rejected instead of ringing up the wrong product.
Making a book barcode? The ISBN barcode generator checks your ISBN for you. Need lots of barcodes from a list? Use the bulk generator.
Frequently asked questions
What is a check digit?
The last digit of a barcode number. It’s worked out from the other digits, so a scanner can tell straight away if a number has been misread or mistyped.
Which barcodes does this work for?
EAN-13, UPC-A, EAN-8 and ITF-14, which are the GTIN family used on retail products and cartons. ISBN-13 uses the same rule as EAN-13. All of them use the same mod 10 method with weights of 3 and 1.
Can I make up my own product barcode numbers?
Not for products sold in shops. Retail numbers must come from GS1, so that no two products share one. A valid check digit only means the number is well formed, not that it’s registered.
Do I need to add the check digit before making a barcode?
No. Our barcode generator adds it for you if you leave it off. This calculator is for when you need the full number itself, for a spreadsheet or a product listing, or want to check one.
Is the number sent anywhere?
No. Everything is worked out in your browser and nothing you type is sent to us or anyone else.