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Barcode Validator

Entered a barcode and not sure if the check digit is correct? This free barcode validator instantly tells you whether a UPC-A, EAN-13, EAN-8, or ITF-14 code is valid - and shows you the correct check digit if it is not. The check digit tab lets you calculate the missing last digit from any GS1-standard code, so you can build complete, scannable barcodes without manual arithmetic. Everything runs in your browser - no files are uploaded.

Detected format: EAN-13

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Valid check digit

No signupRuns in your browserFormula explained belowGeneral information only

How to use this tool

  1. 1Validate tab: Paste or type any barcode value into the input field.
  2. 2The tool auto-detects the format based on length and content (EAN-13, EAN-8, UPC-A, ITF-14, or Code 128/39).
  3. 3For numeric GS1 formats, a green tick confirms the check digit is correct; a red cross shows the expected digit and the corrected code.
  4. 4Check digit tab: Choose your format (EAN-13, EAN-8, UPC-A, or ITF-14) from the dropdown.
  5. 5Enter the payload digits without the check digit - the exact count is shown in the label.
  6. 6The check digit appears instantly, together with the complete barcode and a rendered preview.

Example

Validating an EAN-13 product code

A supplier sends the code 5901234123457. Paste it into the Validate tab. The tool detects EAN-13, recalculates the check digit from the first 12 digits (590123412345), and confirms that 7 is correct - the code is valid.

Calculating a UPC-A check digit

You have 11 digits of a UPC-A code: 01234567890. Switch to the Check digit tab, choose UPC-A, and enter those 11 digits. The tool calculates check digit 5, giving the complete scannable code 012345678905.

Common use cases

  • Verifying a supplier's barcode before printing labels or stickers
  • Calculating the missing check digit when building a product catalogue
  • Confirming that a handwritten or OCR-read barcode was transcribed correctly
  • Checking ITF-14 carton barcodes before shipment to a retailer
  • Testing that a newly generated EAN or UPC passes GS1 validation before going to press

Common mistakes

  • Confusing the full 12-digit UPC-A with the 11-digit payload - the payload does not include the check digit.
  • Entering a UPC-E (6-digit short form) instead of UPC-A - they are different formats and require different handling.
  • Assuming the check digit is always the last printed digit - some scanners suppress it in the human-readable text.
  • Validating an EAN-8 as EAN-13 because both end in a check digit - the tool auto-detects length so this is handled automatically.

Frequently asked questions

What is a barcode check digit?

A check digit is the final digit in a GS1 barcode (UPC, EAN, GTIN, ITF-14). It is mathematically derived from the other digits using an alternating multiply-by-3 and multiply-by-1 sum. Scanners use it to verify that the code was read correctly - a mismatch means a scan error or a typo.

Which formats use GS1 check digits?

UPC-A (12 digits), EAN-13 (13 digits), EAN-8 (8 digits), and ITF-14 (14 digits) all use the same GS1 check digit algorithm. GTIN-14, GTIN-13, GTIN-12, and GTIN-8 are simply GS1 trade item numbers in those same formats.

Does Code 128 have a check digit?

Code 128 has an internal check character computed and embedded by the barcode encoder - you never enter it manually and it is not printed in the human-readable text. This tool validates numeric GS1 formats only; Code 128 and Code 39 are shown with a format note rather than a check digit result.

What if the check digit is wrong - does that mean the product code is fake?

Not necessarily. It more often means a typo, a scan error, or an incorrectly entered code. A valid check digit only proves the digits are internally consistent - it does not verify the code is registered with GS1 or assigned to a real product.

Is my data uploaded to a server?

No. All validation and calculation runs entirely in your browser. No barcode data leaves your device.

Can I validate ISBN barcodes here?

ISBN-13 barcodes use the same EAN-13 check digit, so entering a 13-digit ISBN that starts with 978 or 979 will validate correctly in the EAN-13 validator. For ISBN-specific features like ISBN-10 conversion, use the dedicated ISBN Barcode Generator.

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