Seven-digit body with a zero result
For 1234567, the weighted sum is 60. No additional amount is needed to reach a multiple of 10, so the check digit is0 and the complete value is 12345670.
Local browser tool
GTIN check digit calculator
Calculate a missing GTIN check digit or compare the final digit of a complete number, entirely in your browser.
Calculate a check digit
Choose whether the value includes its final check digit, then enter digits as text.
Result
Calculation evidence
Review the normalized value and each weighted step before copying.
Enter a body or full identifier to see the calculation.
What this result means
The calculator applies the GS1 Modulo-10 formula to the normalized body. In body-only mode it appends the calculated digit. In full-number mode it compares the entered final digit and shows the complete value produced by the calculation.
What this result does not mean
A calculated digit does not issue a GTIN or prove GS1 registration, company ownership, product identity, barcode image quality, physical print grade, certification, or retailer acceptance. Never treat a synthetic example as a commercial identifier.
Supported formats and input modes
- GTIN-8: 7-digit body or 8-digit full number.
- GTIN-12 / UPC-A: 11-digit body or 12-digit full number.
- GTIN-13 / EAN-13: 12-digit body or 13-digit full number.
- GTIN-14: 13-digit body or 14-digit full number.
Auto mode uses length. A 12-digit body or 13-digit full value shares its numeric structure with GLN-13, so business meaning cannot be proven by the check digit alone.
Formula and method
- Start with the rightmost body digit and multiply it by 3.
- Move left, alternating weights 1 and 3.
- Add every weighted product.
- Choose the digit needed to reach the next multiple of 10.
The compact formula is(10 - (weighted sum mod 10)) mod 10. The workbench exposes each position, weight and product so the result can be reproduced.
Worked examples
Leading zero retained
The body 01234500005 produces check digit8. The complete string is 012345000058; converting it to a number would incorrectly discard the first digit.
Readable separators normalized
Entering 629 104-150021 shows the normalized body629104150021. Its check digit is 3. The original and normalized values remain visible as separate evidence.
TEST / SYNTHETIC / NOT FOR COMMERCIAL USE. Examples demonstrate the formula and do not establish assignment.
Common errors
- Using the full number in body-only mode
- Select full-number mode or remove only the final check digit.
- Dropping a leading zero
- Paste and store the value as text, not a spreadsheet number.
- Selecting the wrong GTIN type
- Correct the type or length; the tool will not pad or truncate it.
- Including unsupported punctuation
- Only whitespace and common dash separators are normalized.
Privacy and local processing
Calculation happens in the loaded page. The input is not placed in the URL, analytics, storage, logs, or a network request. Copying occurs only when you choose a copy action.
Sources and review
Method reviewed 2026-07-13 against GS1 General Specifications 26.0.0 (January 2026) and the officialmanual calculation guide. BarcodeOpsKit is not affiliated with GS1.
Related tool and reading
Validate a complete GTIN, UPC or EANor read how GS1 check digits work. TheGS1 check digit overview remains the primary external reference.
Frequently asked questions
Can this tool create an official GTIN?
No. It calculates a final digit but does not issue or register a number.
Why does a 13-digit value have more than one possible meaning?
GTIN-13 and GLN-13 share the same length and check-digit algorithm. Business context or registry evidence is needed to distinguish them.
Does a matching digit prove that a printed barcode will scan?
No. Symbol encoding, dimensions, quiet zones, contrast and print quality are separate checks.