A GTIN check digit helps detect common manual entry errors. It is calculated from the preceding digits using alternating weights of 3 and 1, counting from the rightmost digit of the body.

Worked example

For the 12-digit body 400638133393, the weighted sum is 89 and the check digit is 1, yielding EAN-13 4006381333931. The resulting number is mathematically valid, but the calculation does not assign the number to a company.

Validation is not allocation

Use the calculator to catch input errors before producing EAN-13, UPC-A or ITF-14 labels. Check official GS1 allocation and business partner requirements separately.

Frequently asked questions

Can the check digit prove a product is authentic?

No. It detects some data-entry mistakes; it does not establish ownership, authenticity or GS1 allocation.

Does the same algorithm work for GTIN-8, 12, 13 and 14?

Yes, the GS1 modulo-10 weighted calculation is used for these GTIN lengths.

Why does my result differ?

Check that leading zeros were retained and that you entered the body digits rather than including an existing check digit twice.

How the GS1 modulo-10 check digit works

Worked EAN-13 example

For 400638133393, the weighted sum of the first 12 digits is 89. The smallest digit that makes the sum a multiple of ten is 1, so the complete number is 4006381333931.

What the check digit can and cannot prove

A valid check digit detects many typing mistakes. It does not prove that a GTIN is unique, assigned by GS1, active or associated with the product you are scanning.

GTIN-8, GTIN-12, GTIN-13 and GTIN-14

The same modulo-10 principle applies across these lengths. Weight digits alternately from the right, beginning with 3 for the rightmost data digit; then calculate the complement to the next multiple of ten.

Independent general-purpose tool

Whether a generated barcode can be used at work depends on your workplace rules and scanner settings.