Barcode Check Digit Calculator — GTIN-8/12/13/14
Instantly calculate modulo-10 check digits for EAN-8, UPC-A, EAN-13, and ITF-14 numbers.
Check Digit Calculator
Official GS1 Modulo-10 algorithm for GTIN barcodes.
GS1 Modulo-10 Check Digit
Calculated from 12 payload digits
1. Weighted Sum = 83
2. Sum % 10 = 3
3. Check Digit = (10 - 3) % 10 = 7
Calculated entirely in your browser. GTIN data and check digits are validated locally on your device with zero telemetry or network calls.
How to Use
- Select your barcode standard (EAN-13, UPC-A, EAN-8, ITF-14, or universal custom length).
- Enter your payload digits without the final check digit.
- The calculator automatically computes the GS1 Modulo-10 checksum in real-time.
- Review the mathematical step-by-step breakdown (multipliers, sum, and modulo result).
- Copy the complete code or jump directly to the barcode generator to export SVG/PNG graphics.
About This Format
The GS1 Modulo-10 check digit is an algorithmic safeguard applied to all GTIN barcode numbers (including GTIN-8, GTIN-12, GTIN-13, and GTIN-14). By applying alternating weights of 3 and 1 from right to left across payload digits, the algorithm generates a single checksum digit that detects 100% of single-digit entry errors and over 90% of transposition errors (swapped digits).
Validation & Technical Constraints
- Only numeric digits (0–9) are allowed.
- Payload length must match the expected standard: 7 digits for EAN-8, 11 for UPC-A, 12 for EAN-13, 13 for ITF-14.
- Universal mode allows check digit calculation for arbitrary numeric sequences.
Examples
EAN-13 (12 digits in → check digit 7)
590123412345
UPC-A (11 digits in → check digit 5)
01234567890
EAN-8 (7 digits in → check digit 4)
9638507
Frequently Asked Questions
Starting from the rightmost digit of the payload, digits in odd positions from the right are multiplied by 3, while digits in even positions are multiplied by 1. All products are added together. The check digit is the amount needed to round the total sum up to the nearest multiple of 10: (10 - (sum % 10)) % 10.
Check digits protect against scanning errors and human mistypes. If a single digit is smudged or misread by an optical scanner, or if two adjacent numbers are transposed during manual entry, the check digit math will not match and the scanner rejects the read instead of charging for the wrong product.
No. This calculator computes the mathematical checksum for a number you provide. To use barcodes on retail products legally, your company must license an authorized GS1 company prefix.