Barcode Check Digit Calculator
Enter the body of a UPC, EAN or GTIN and we'll compute the correct check digit — with a full step-by-step breakdown.
All math happens in your browser. Nothing is uploaded.
Result
Enter the body digits and the check digit will appear here, with the full weighted-sum breakdown.
Supported barcode types
The calculator handles every GTIN length that uses the GS1 mod-10 algorithm.
Small retail packages where space is tight.
Standard US and Canadian retail barcode.
Global retail standard outside North America.
Cases, cartons and pallets in logistics.
Examples
Verified samples for every supported format. The complete code is the body with the calculated check digit appended.
| Format | Body | Check digit | Full code |
|---|---|---|---|
| GTIN-8 | 7351353 | 7 | 73513537 |
| GTIN-12 | 03600029145 | 2 | 036000291452 |
| GTIN-13 | 501234567890 | 0 | 5012345678900 |
| GTIN-14 | 1061414100041 | 5 | 10614141000415 |
About this barcode check digit calculator
This barcode check digit calculator computes the final digit of a UPC-A, EAN-13, EAN-8 or GTIN-14 barcode using the GS1 mod-10 algorithm. Paste the body digits — everything except the trailing check digit — and the tool returns the missing digit, the complete code, and a step-by-step breakdown of how the result was reached.
Use it whenever you need to calculate a GTIN check digit by hand, verify what a printed barcode should end with, or generate a fresh code from a body issued by your numbering authority.
When to use it
- Generating a new EAN-13 from an issued 12-digit body before sending it to a label printer.
- Calculating a UPC check digit when a supplier sent you only the first 11 digits.
- Building a GTIN-14 carton code on top of an inner GTIN-13.
- Recomputing a check digit after correcting a typo in the body.
- Teaching a teammate how the GS1 mod-10 algorithm actually works.
How it works
- Pick a format
Choose GTIN-8/12/13/14, or leave Auto-detect on and we'll pick by length.
- Paste the body
Enter the digits without the check digit. Spaces, dashes and dots are stripped.
- We weight each digit
Walking from right to left, odd positions get ×3, even positions get ×1.
- We sum and round up
The weighted sum is rounded up to the next multiple of 10.
- You get the check digit
The difference between the rounded value and the sum is your check digit. Copy the full code in one click.
What to avoid
- Pasting the full barcode including the existing check digit — use the GTIN Validator for that.
- Mixing UPC-A and UPC-E lengths — UPC-E needs to be expanded first.
- Trusting hand-computed digits without re-verifying; one digit off cascades through the whole code.
- Treating the calculator as a product database — it doesn't look up names or prices.
- Generating a GTIN body yourself; bodies must come from a GS1-assigned prefix.
Tips & tricks
- If Auto-detect picks the wrong format, switch the dropdown to the format you intend.
- Click an example below to see the full step-by-step breakdown instantly.
- When the sum is already a multiple of 10, the check digit is 0 — not 10.
- For ITF-14, the leading 'indicator digit' (1–8) is part of the body and is weighted ×3.
- Pair this with the GTIN Validator to confirm an existing code after you've calculated the check digit.