How to use this calculator
Start with the deterministic fixture values already shown, then replace each input with measurements from your job. Use consistent units and review the highlighted assumptions before using the result in purchasing or production.
Formula and method
Starting at the rightmost body digit, multiply alternating digits by 3 and 1, add the products, and choose the digit that completes the next multiple of ten.
Worked example
For body 1001234500001, the weighted sum requires check digit 7, producing GTIN-14 10012345000017.
How to interpret the result
GTIN-14 is commonly used to identify trade-item groupings. The first digit can participate in packaging-level numbering, but allocation decisions remain with the responsible GS1 licence holder.
Limitations
A valid check digit does not confirm ownership, allocation, product data, packaging level or authorization to use the number.
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