UPC check digit calculator
Calculate or validate the GS1 mod-10 check digit for UPC-A, EAN-13, EAN-8, and GTIN-14. One number, a pasted list, or a CSV. The math runs in this tab. Nothing is uploaded.
Valid retail barcodes must be licensed from GS1 (gs1.org / your local GS1 member organisation). These tools only compute and draw barcodes; we do not sell barcode numbers.
Twelve digits can be a finished UPC-A or an EAN-13 that still needs its check digit. Auto shows both readings. Pick a format when you already know which one you have. To draw the bars, use the EAN-13 barcode generator.
One code
Enter 7–14 digits. The check digit is the last one, or it is added when you leave it off.
List or CSV
One code per line, or a CSV with a barcode / upc / ean / gtin / code column. An optional format column overrides the menu for that row. The same format menu applies when a row does not name one.
Results
| Input | Format | Role | Status | Check | Full code | GTIN-14 | Note |
|---|
How the digit is chosen
- UPC-A is 12 digits, EAN-13 is 13, EAN-8 is 8, and GTIN-14 is 14. The last digit is the check digit. Give the tool one fewer digit and it calculates that digit. Give it the full length and it validates.
- Weights start at 3 on the digit next to the check digit and then alternate 1, 3, 1, 3 toward the left. The check digit is
(10 − (sum mod 10)) mod 10. - Known examples: UPC-A
036000291452, EAN-134006381333931and ISBN-139780306406157, EAN-896385074, GTIN-1400012345600012. - Shorter GTINs pad to GTIN-14 with zeros on the left. The check digit stays the same because those zeros do not change the weighted sum.
- A correct check digit does not license the number. Retail barcodes come from GS1 or your local GS1 member organisation.
Check digit questions
How does the UPC check digit calculator work?
The last digit of a UPC-A, EAN-13, EAN-8, or GTIN-14 is a GS1 modulo-10 check digit. From the digit immediately left of the check digit, moving left, multiply by 3, then 1, then 3, and so on. Add those products. The check digit is what you add to reach the next multiple of 10, or 0 if the sum already ends in 0. This page does that math in your browser.
What is an EAN-13 check digit?
An EAN-13 is 13 digits. The first 12 are the data and the 13th is the check digit, using the same GS1 mod-10 rule as UPC-A. Enter 12 digits and this tool appends the check digit. Enter 13 and it says whether the last digit is correct. For example, 400638133393 has check digit 1, so the full code is 4006381333931.
How do UPC-A, EAN-13, EAN-8, and GTIN-14 relate?
UPC-A (GTIN-12) is 12 digits and is common in the US and Canada. EAN-13 (GTIN-13) is 13 digits and is the usual retail code elsewhere. EAN-8 (GTIN-8) is 8 digits for small packages. GTIN-14 is 14 digits, used on cases and in many inventory files. Adding zeros on the left to make 14 digits does not change the number or the check digit. A UPC-A is the same key as an EAN-13 with a leading 0.
Does a valid check digit mean the number is mine to use?
No. A matching check digit only means the number is internally consistent. It does not mean GS1 issued it to you, and it does not mean it is free to put on a product. Valid retail barcodes must be licensed from GS1 (gs1.org / your local GS1 member organisation). These tools only compute and draw barcodes; we do not sell barcode numbers.
Can I check a list or a CSV?
Yes. Paste one code per line, or upload a CSV. A header is recognized when a column is named barcode, upc, ean, gtin, or code. An optional format column can say UPC-A, EAN-13, EAN-8, or GTIN-14. Semicolons are accepted when the file has no commas. The check runs in this tab. Download the results as CSV. Nothing is uploaded.
Why did Excel change my barcode number?
Excel drops leading zeros and may show a long number in scientific notation if the column is not Text. Format the column as Text before you paste, or import the CSV with that column typed as text. This tool cannot restore a zero that Excel already removed. Spaces and hyphens in the number are ignored.
Where does the code go on a Shopify product CSV?
Put the full code, including the check digit, in the Barcodes column (Barcode or Variant Barcode on older templates). Keep the column as text so a leading zero survives. Then check the file with the free Shopify CSV validator before you import. To draw the symbol, use the EAN-13 barcode generator.
Need the file cleaned for you?
If the catalog is more than a check digit — broken handles, missing option columns, a supplier sheet that is not a Shopify CSV — catalog.csv maps it to an import-ready product file. File-only, no store login. Free 2-row test, then you pay only after it imports.
Done-for-you Shopify CSV cleanup