Check digit calculator

All GTINs need a check digit, and this is the last digit of the number.  The check digit is calculated from all the preceding digits, and it is used by any scanning system to check that the number scanned in from a barcode is correct.  This calculator can be used to work out the check digit for your GTINs, and for the 18-digit SSCC (serial shipping container code) used to identify logistics units.


Choose the appropriate GTIN or SSCC option from the dropdown list opposite.  The table below explains which GTINs usually appear in which GS1 barcodes.  Remember that a leading zero in front of a GTIN-13 does not change the number, but simply allows it to be printed in a barcode that requires 14-digits, such as an ITF-14 or GS1-128 barcode.

Type pf number Type of barcode that can encode it
GTIN-12 UPC-A (also GS1 DataMatrix and GS1 QR)
GTIN-13 EAN-13 (ITF-14, GS1-128, GS1 DataMatrix, and GS1 QR)
GTIN-14 ITF-14 (GS1-128, GS1 DataMatrix, GS1 QR)
SSCC GS1-128

Other GS1 identifiers also need a check digit to complete them, and this calculator can also provide these for the following GS1 keys.


Global Location Number (GLN), Global Returnable Asset Identifier (GRAI), Global Coupon Number (GCN), Global Document Type Identifier (GDTI).  These all incorporate, at least, a 13-digit number and the check digit is the same as that for a GTIN-13.


Global Service Relation Number (GSRN).  This is an 18-digit number and the check digit is the same as that for an SSCC.


Global Shipment Identification Number.  This is a 17 digit number.  Place a leading zero in front of it, and then use the SSCC check digit calculator.


Symbology Code Result

The check digit result is calculated using the information submitted. Please ensure you have entered all numerical data accurately as Axicon cannot be held responsible for incorrect data entry.

How to calculate your check digit yourself


Example barcode number: 501234576421


Step 1: add together all alternate numbers starting from the right

5 0 1 2 3 4 5 7 6 4 2 1

0 + 2 + 4 + 7 + 4 + 1 = 18


Step 2: multiply the answer by 3

18 x 3 = 54


Step 3: now add together the remaining numbers

5 0 1 2 3 4 5 7 6 4 2 1

5 + 1 + 3 + 5 + 6 + 2 = 22


Step 4: add step 2 and 3 together

54 + 22 = 76


Step 5: the difference between step 4 and the next 10th number:

76 + 4 = 80

Check digit = 4

Check digit


Contact us

Axicon Logo

See also

Barcode images

Barcode FAQ

15000 series barcode verifiers

The Axicon 6500 series barcode verifier is designed to verify linear barcodes with a maximum width of 125 mm.

The Axicon 7015 barcode verifier is designed to verify large linear barcodes up to 195mm

The Axicon 15000 series verifiers have been designed to read both two-dimensional and linear barcodes.

Axicon Logo

Useful links

Get in touch with us

Axicon Auto ID is a world leader in barcode verification, having developed and manufactured our own range of verifiers since 1989. Axicon barcode verifiers are used to measure the quality of linear and matrix barcodes, on all levels of product packaging.




+44 (0)1869 351155

+01 (434) 939 9647

Weston on the Green


OX25 3QP, UK

Contact us

© 2024 Axicon Auto ID Limited

Axicon Logo
Axicon Logo
Axicon Logo
Axicon Logo
Axicon Logo