BYTETOOLS

Barcode Check Digit Calculator

Calculate or verify the GS1 check digit for EAN-13, EAN-8, UPC-A, UPC-E, GTIN-14, ITF-14 and SSCC-18, one code at a time or a whole pasted list.

Result

Enter a barcode number. Everything is calculated locally in your browser — nothing is uploaded.

What is the Barcode Check Digit Calculator?

The ByteTools Barcode Check Digit Calculator applies the GS1 modulo-10 rule that every EAN, UPC, GTIN and SSCC shares.

  • Seven symbologies: EAN-13, EAN-8, UPC-A, UPC-E, GTIN-14, ITF-14 and SSCC-18
  • Calculates a missing check digit or verifies a complete code
  • Automatic symbology detection from the digit count
  • UPC-E expanded to its UPC-A form before the check digit is computed
  • Step-by-step weighting table showing the ×3 / ×1 alternation
  • Batch mode with a copyable report, all computed offline

How to use the Barcode Check Digit Calculator

  1. 1

    Type or paste the barcode number into the top box.

  2. 2

    Leave the symbology on 'Detect from the number of digits', or pick one explicitly — required for UPC-E.

  3. 3

    Enter a complete code to verify it, or leave off the final digit to have it calculated.

  4. 4

    Read the working table to see exactly which digits took the ×3 and ×1 weights.

  5. 5

    Paste a list into the batch box for one verdict per line, then copy the report.

About the Barcode Check Digit Calculator

The ByteTools Barcode Check Digit Calculator applies the GS1 modulo-10 rule that every EAN, UPC, GTIN and SSCC shares. Working right to left across the digits, each is multiplied alternately by 3 and 1 so the check digit itself always carries a weight of 1; the products are added, and the check digit is whatever brings the total up to the next multiple of ten.

Leave the last digit off and the tool calculates it. Include it and the tool verifies it, telling you the correct digit when it does not match. UPC-E is handled properly too: because it is a zero-suppressed UPC-A, the check digit belongs to the expanded twelve-digit form, which the page reconstructs and shows you.

It is built for anyone assigning GTINs, cleaning up a product feed, printing carton labels or debugging a scanner. A batch box processes a whole pasted list. Everything is calculated 100% locally in your browser — no barcode you enter is ever uploaded.

Frequently asked questions

How is an EAN-13 check digit calculated?

Take the first twelve digits, multiply them alternately by 3 and 1 working from the right, and add the products. The check digit is the number that raises that total to the next multiple of ten — so a total of 89 gives a check digit of 1.

Do UPC-A and EAN-13 use the same check digit?

Yes, the arithmetic is identical. A UPC-A is simply a GTIN-13 with a leading zero, so putting a zero in front of a valid UPC-A gives a valid EAN-13 with the same final digit.

Why is UPC-E different?

UPC-E is a compressed form of UPC-A with zeros squeezed out, and its check digit belongs to the full twelve-digit number, not the eight printed digits. This tool expands it using the GS1 zero-suppression table first, and shows you the expanded code.

What does an invalid check digit mean?

Almost always that a digit was mistyped or misread. The check digit exists to catch exactly that, so a mismatch is a strong sign the number is wrong somewhere — although it cannot tell you which of the earlier digits is at fault.

Can I check a list of barcodes at once?

Yes. Paste one code per line into the batch box and each gets its own verdict, which you can copy out as a tab-separated report for a spreadsheet.

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