Short answer: type the first 12 digits of an EAN-13 and the calculator returns the 13th, the check digit; type all 13 to test a number. The method is modulo 10: weight the 12 digits 1, 3, 1, 3 and so on from the left, add the products, and the check digit is the amount that brings the sum up to the next multiple of ten (0 if it is already one). A correct check digit shows the number is composed correctly; it does not show the number was issued to you.
Find or check an EAN-13 check digit
Worked examples
| First 12 digits | Weighted products | Sum | Next multiple of ten | Check digit | Full EAN-13 |
|---|---|---|---|---|---|
| 952012345678 | 9 + 15 + 2 + 0 + 1 + 6 + 3 + 12 + 5 + 18 + 7 + 24 | 102 | 110 | 8 | 9520123456788 |
| 400638133393 | 4 + 0 + 0 + 18 + 3 + 24 + 1 + 9 + 3 + 9 + 9 + 9 | 89 | 90 | 1 | 4006381333931 |
| 952012345687 | 9 + 15 + 2 + 0 + 1 + 6 + 3 + 12 + 5 + 18 + 8 + 21 | 100 | 100 | 0 | 9520123456870 |
The first row is the example on our EAN-13 guide. The second is the worked example in the Wikipedia article. The third is our own arithmetic example, picked so the sum is already a multiple of ten and the check digit is 0. All three are for demonstration and are not numbers issued to any product.
Check a whole list
What the check digit does and does not tell you
- It is calculated from the other 12 digits and cannot be chosen. It confirms the number is composed correctly.
- It does not show that the number belongs to you. The company prefix, which starts 890 for GS1 India, and the length of the item reference come from your GS1 India licence, so ask GS1 India for the lengths that apply to you.
- Each SKU needs its own item reference. If two frame sizes are separate SKUs, they need two numbers, and the register template below keeps one line per SKU.
- Run every number through a calculator before packaging artwork goes to print, and check the method against the current GS1 General Specifications.
Download the SKU and barcode register (CSV)
Method sources: GS1 US, How to calculate a check digit (multiply each position by its weight, add the results, subtract the sum from the nearest equal or higher multiple of ten) and Wikipedia, International Article Number (the check digit is computed modulo 10 with weights alternating 3 and 1, counted from the right; the leftmost of the first 12 digits has weight 1). Both give the same result for a 12-digit body.
Related: how an EAN-13 number is built, GS1 barcodes for products sold in India, barcode size and placement on packaging, the SKU and barcode register.
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Sources: how an EAN-13 number is built [S26]. As of 2026-11-12. Terms are typical and are confirmed in your written quote.