Barcode Check Digit Calculator

Written byOleh Soloninupdated 5 October 2026

Code digits

Format

Result

Check digit3
Full code4601234567893
Validationno check digit was supplied
FormatEAN-13
Weighted sum117
First three digits460

The last digit is a test, not data

Calculates the EAN-13, EAN-8 or UPC-A check digit and verifies whether a full barcode was entered correctly.

The final digit of a barcode carries no information about the product. It is arithmetic: a weighted sum of the digits before it, chosen so that the whole code adds up to a multiple of ten.

That single digit catches every single-digit error and most transpositions, which is exactly what happens when a code is typed by hand or read badly.

How to use

Pick the format: EAN-13, EAN-8 or UPC-A.
Enter the code without the check digit to calculate it, or with it to verify.
Look at the weighted sum: it shows where the digit came from.
To verify someone else's code, type it in full — the calculator says whether it adds up.

Where the check digit comes from

Each row is a run of this calculator in EAN-13. Digits are weighted 3 and 1 alternately from the right, summed, and the check digit tops the sum up to the next multiple of ten.

For 460123456789 the weighted sum is 117, the next ten is 120, so the check digit is 3. That is why a single wrong digit is always caught, while a swap of two adjacent digits is caught only if they differ by something other than five — the known gap in the method.

Runs of this calculator in EAN-13.
Code without check digit	Weighted sum	Check digit	Full code
460123456789	117	3	4601234567893
978014300723	86	4	9780143007234

What this calculator shows

The check digit and the complete code
Whether a supplied full code passes the test
The weighted sum behind the calculation and the first three digits

What to keep in mind

Digits are weighted 3 and 1 alternately, counting from the right of the body of the code.
The first three digits are the GS1 prefix. They identify the numbering organisation that issued the code, not necessarily where the product was made.

FAQs

What do the first three digits mean?

They are the GS1 prefix of the issuing organisation. 460 to 469 is Russia, 400 to 440 Germany, 50 the United Kingdom — but a code says where it was registered, not where the goods were made.

What errors does it catch?

Every single wrong digit, and most swaps of neighbouring digits. A swap of neighbours that differ by five slips through, as does a swap of digits one apart — they carry the same weight — and some errors in several digits at once.

Is EAN-13 the same as UPC-A?

Nearly. UPC-A is twelve digits and is an EAN-13 with a leading zero; the check digit arithmetic is identical.

How is the check digit calculated?

Digits are multiplied alternately by 3 and 1 from the right and added up; the check digit is (10 − the sum mod 10) mod 10, so 0 when the sum is already a multiple of ten. At a sum of 117 that is 3.

Which errors does the method miss?

A swap of two adjacent digits that differ by five — 1 and 6, for instance. A single wrong digit on its own is always caught.

Worked example

A thirteen-digit code

Input: 460123456789

Output: check digit 3, the full code 4601234567893

Note: The weighted sum is 117, and the next multiple of ten is 120 — three away. Change any single digit and the sum stops landing on a multiple of ten.

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