GTIN Check Digit Calculator — EAN / UPC Barcode
Enter the barcode digits — with or without the check digit — to compute a GTIN check digit or validate an existing one. Supports EAN-8, UPC-A (GTIN-12), EAN-13 and GTIN-14.
Digit 1: 5 × 1 (even pos → ×1)
Digit 2: 9 × 3 (odd pos → ×3)
Digit 3: 0 × 1 (even pos → ×1)
Digit 4: 1 × 3 (odd pos → ×3)
Digit 5: 2 × 1 (even pos → ×1)
Digit 6: 3 × 3 (odd pos → ×3)
Digit 7: 4 × 1 (even pos → ×1)
Digit 8: 1 × 3 (odd pos → ×3)
Digit 9: 2 × 1 (even pos → ×1)
Digit 10: 3 × 3 (odd pos → ×3)
Digit 11: 4 × 1 (even pos → ×1)
Digit 12: 5 × 3 (odd pos → ×3)
Sum of products
Check digit
How does this calculator work?
The GS1 check digit: multiply each payload digit by alternating weights (3 and 1, starting from the rightmost), sum the products, subtract the remainder from 10 (mod 10). Enter 7–13 payload digits to compute, or 8–14 full digits to validate a GTIN.
Formula
How this is calculated
Every GS1 barcode (EAN, UPC, GTIN-14) ends with a check digit computed by the GS1 modulo-10 algorithm, sometimes called the Luhn mod-10 variant. Starting from the rightmost payload digit and moving left, digits at odd positions (1, 3, 5, …) from the right are multiplied by 3, and digits at even positions (2, 4, 6, …) by 1. All products are summed, and the check digit is chosen so that (sum + check digit) is divisible by 10 — equivalently, check = (10 − sum mod 10) mod 10. If the sum is already a multiple of 10 the check digit is 0.
The same algorithm covers all GTIN lengths: GTIN-8 (EAN-8 for small items), GTIN-12 (UPC-A, the standard North American retail barcode), GTIN-13 (EAN-13, the global standard), and GTIN-14 (for logistic units and cases). Enter 7, 11, 12, or 13 digits (payload without the final check digit) to compute the check digit, or enter the full 8, 12, 13, or 14-digit barcode to validate it.
The step-by-step trace below the result shows every multiply-and-add operation, making it easy to verify a hand calculation or to understand why a barcode scanner rejects a specific number.
Frequently asked questions
A single digit transposed or misread causes a check-digit mismatch, and scanners reject the code immediately. Paste the full barcode here — if the check digit shown does not match the last digit you entered, a digit is wrong somewhere.
Yes — ISBN-13 is a GTIN-13 with the prefix 978 or 979. The check digit algorithm is identical. Enter the 12 payload digits (everything except the last digit) to compute or verify the ISBN-13 check digit.
UPC-A is a 12-digit barcode used predominantly in North America; EAN-13 is the 13-digit international standard used everywhere else. GTIN-12 and GTIN-13 are the GS1 standard names for the same things. EAN-13 with a leading zero is effectively a 12-digit UPC-A padded to 13 digits.
Also known as
TG we-Calculate Editorial Team. (2026). GTIN Check Digit Calculator — EAN / UPC Barcode [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/gtin-check-digit-calculator
TG we-Calculate Editorial Team. "GTIN Check Digit Calculator — EAN / UPC Barcode." TG we-Calculate. 2026. https://we-calculate.com/calculator/gtin-check-digit-calculator.
TG we-Calculate Editorial Team, "GTIN Check Digit Calculator — EAN / UPC Barcode," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/gtin-check-digit-calculator
@misc{wecalculate_gtin_check_digit_calculator, title = {GTIN Check Digit Calculator — EAN / UPC Barcode}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/gtin-check-digit-calculator}}, year = {2026}, note = {TG we-Calculate} }
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