LINKMINT PRACTICAL GUIDE
EAN and UPC Check Digits: Calculation and Validation
A check digit catches many typing errors, but a mathematically valid number does not prove that a product identifier is assigned to you.
Published and reviewed 5 October 2026 · By the LinkMint Editorial Team · How we test and review
EAN-8, UPC-A, EAN-13 and ITF-14 carry fixed-length numeric identifiers. Their final digit is a check digit calculated from the earlier digits. Barcode software can validate that arithmetic before drawing the bars.
The GS1 modulo-10 method
- Starting from the rightmost data digit, multiply alternating digits by 3 and 1.
- Add all weighted values.
- Find the smallest number that brings the total up to a multiple of 10.
- That number, from 0 to 9, is the check digit.
Worked EAN-13 example
Take the twelve data digits 400638133393. From the right, alternating weights of 3 and 1 produce a weighted total of 89. The next multiple of ten is 90, so the check digit is 1. The complete EAN-13 value is 4006381333931.
A validator that receives all 13 digits repeats the calculation and checks that the supplied final digit is 1. If you edit any data digit, calculate a new check digit rather than keeping the old one.
Lengths supported by LinkMint
| Symbol | Data digits before check | Complete value | Common context |
|---|---|---|---|
| EAN-8 | 7 | 8 digits | Small retail items when an assigned GTIN-8 is appropriate |
| UPC-A / GTIN-12 | 11 | 12 digits | Retail scanning, especially in North America |
| EAN-13 / GTIN-13 | 12 | 13 digits | Retail trade items in many markets |
| ITF-14 / GTIN-14 | 13 | 14 digits | Higher-level packaging and distribution |
What validation does and does not prove
A correct check digit indicates that the digits are internally consistent. It can catch many single-digit mistakes and transpositions. It does not look up a product, confirm ownership, assign a number or guarantee that a retailer will accept the symbol. Product identification starts with the identifier allocated through the relevant GS1 member organisation or another process required by the receiving system.
A pre-print validation checklist
- Confirm the complete identifier in the authoritative product record.
- Choose the barcode symbology required by the retailer, warehouse or software.
- Check the number length and final check digit.
- Generate the barcode without stretching or cropping its quiet areas.
- Print a sample at the intended size and material.
- Scan into the real receiving application and verify the returned product.
The LinkMint Barcode Generator validates supported lengths and check digits. It intentionally rejects a complete EAN or UPC value with an incorrect final digit.
Primary source: GS1 General Specifications, check digit calculations.