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UPC Check Digit Calculator

Calculate a UPC-A check digit from 11 digits or validate a complete 12-digit UPC-A / GTIN-12. Enter your known values; results update as you type.

Inputs

Leading zeros are preserved. UPC-A uses numeric digits only.

Calculated result

Identifier typeUPC-A / GTIN-12
Check digit2
Complete number036000291452
5×3 + 4×1 + 1×3 + 9×1 + 2×3 + 0×1 + 0×3 + 0×1 + 6×3 + 3×1 + 0×3 = 58 Check digit = (10 − (58 mod 10)) mod 10 = 2
This calculator checks modulo-10 arithmetic only. It does not verify allocation, ownership, licensing, or GS1 certification.

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

UPC-A uses the GS1 modulo-10 method. From the rightmost body digit, alternating weights 3 and 1 are applied before the final digit completes a multiple of ten.

Read the methodology and source notes →

Worked example

UPC-A body 03600029145 has check digit 2, producing the complete number 036000291452.

How to interpret the result

Use validation to catch many typing errors before creating or checking a UPC-A symbol. Preserve leading zeros.

Limitations

Checksum validity does not establish that a UPC was licensed, assigned to the stated product or encoded with compliant dimensions.

Optional partner module · disabledCategory placeholder: measuring tools. No products, reviews, prices or outbound links are configured.

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