GTIN Check Digit
Calculate GTIN-8/12/13/14 barcode check digits using the GS1 modulo 10 algorithm. Free online calculator for EAN-8, UPC-A, EAN-13, and ITF-14 barcodes.
About This Calculator
The GTIN Check Digit Calculator computes the final check digit for Global Trade Item Number (GTIN) barcodes using the standard GS1 modulo 10 algorithm. This free online tool supports all common GTIN formats including GTIN-8 (EAN-8), GTIN-12 (UPC-A), GTIN-13 (EAN-13), and GTIN-14 (ITF-14). It is essential for manufacturers, retailers, supply chain professionals, and anyone involved in product identification and barcode creation who needs to ensure barcode integrity and compliance.
The check digit is calculated using a weighted sum algorithm. Starting from the leftmost digit of the code, each digit is alternately multiplied by weights of 1 and 3 (odd positions get weight 1, even positions get weight 3). All weighted values are summed together, and the check digit is the smallest number that makes the total a multiple of 10. If the code does not fill all the digit positions, leading zeros are automatically added. For example, to calculate a GTIN-13 check digit for code 112345567809, the odd positions (1,1,2,4,5,7,0) are summed to 19, the even positions (1,3,5,6,8,9) are summed to 32 and multiplied by 3 to get 96, giving a total of 115, and the check digit is 120 minus 115, which equals 5.
Regional Notes
GTIN standards are developed and maintained by GS1, a global organization with member organizations in over 100 countries. GTIN-12 (UPC-A) is standard in the United States and Canada, while GTIN-13 (EAN-13) is the international standard used everywhere else including the UK, Europe, India, Australia, and most of Asia. GTIN-8 is used globally for small items where space is limited. The check digit calculation algorithm is identical worldwide, so no region-specific variations exist.
Frequently Asked Questions
What is a GTIN check digit?
A GTIN check digit is the final digit of a Global Trade Item Number (GTIN) barcode. It is calculated from the preceding digits using a modulo 10 algorithm with alternating weights of 1 and 3. The check digit ensures barcode integrity by detecting common data entry errors such as single-digit mistakes and adjacent digit swaps.
How is the GTIN check digit calculated?
Starting from the leftmost digit of the code (excluding the check digit), multiply each digit alternately by 1 and 3 (odd positions by 1, even positions by 3). Sum all the products. The check digit is the smallest number that, when added to the sum, makes the total a multiple of 10. Mathematically, check digit = (10 - sum % 10) % 10.
What are the different GTIN formats?
GTIN-8 (EAN-8) is an 8-digit shortened barcode used for small products. GTIN-12 (UPC-A) is a 12-digit barcode primarily used in North America. GTIN-13 (EAN-13) is a 13-digit barcode used internationally for retail products. GTIN-14 (ITF-14) is a 14-digit barcode used for wholesale shipping containers and trade items.
What are the weights used in the GTIN check digit algorithm?
The GTIN check digit uses alternating weights of 1 and 3. The leftmost digit (position 1) is multiplied by 1, position 2 by 3, position 3 by 1, position 4 by 3, and so on. This weighted sum approach ensures that both single-digit errors and most adjacent digit transpositions are detected.
Can the GTIN check digit detect all errors?
No, the GTIN check digit cannot detect all errors. It can detect any single-digit error and most adjacent digit transpositions, but it cannot detect some specific double transposition errors. It is designed as a quick integrity check for manual data entry, not a cryptographic security measure.
What happens if I enter more digits than expected?
If you enter more digits than the GTIN format supports (e.g. entering 13 digits for a GTIN-12), the calculator will not produce a result. Each GTIN format has a specific number of digits, and the code entered must not exceed that count. Enter only the digits before the check digit.
How do I verify if an existing barcode has the correct check digit?
Remove the last digit (the check digit) from the barcode, enter the remaining digits as the code, and select the appropriate GTIN format. Click Calculate Check Digit. If the calculated check digit matches the removed digit, the barcode has a valid check digit.
Is this GTIN check digit calculator free to use?
Yes, this GTIN check digit calculator is completely free to use. There are no hidden charges, no account required, and no usage limits. You can calculate as many barcode check digits as you need.