UPC barcodes: what the 12 digits mean and how to make a UPC-A
UPC-A is the 12-digit barcode on products sold in the United States and Canada. It's read at the till, and the number behind it identifies one product from one company.
Where the number comes from
Retailers expect UPC numbers licensed from GS1, the organisation that runs the system. You join GS1 US (or your country's GS1), get a company prefix, and number your products from it. Numbers bought cheaply from resellers may be rejected by large retailers and marketplaces, because the registered owner isn't you.
What the 12 digits mean
- Company prefix (6 to 10 digits): identifies your company.
- Item reference: the digits you assign, one number per product, size and colour.
- Check digit (the last digit): calculated from the other eleven so scanners can catch misreads.
The check digit
Add the digits in odd positions and multiply by 3, add the digits in even positions, then pick the digit that brings the total to the next multiple of 10. You don't need to do it by hand: the UPC-A generator calculates it, and warns you if a number you type has the wrong one.
Size and printing
- The standard size is about 37.3 mm wide and 25.9 mm tall including the numbers. GS1 allows scaling roughly from 80% to 200%.
- Don't cut the bar height: short, wide barcodes scan worse.
- Leave the blank margins at both sides. The scanner needs them.
- Black bars on white are safest. Red bars don't scan, because scanners use red light.
UPC-A, UPC-E or EAN-13?
UPC-E is a shortened 8-digit form for very small packs, made from certain UPC-A numbers with zeros. EAN-13 is the 13-digit version used outside North America; a UPC-A is the same as an EAN-13 starting with 0, and scanners in North America read EAN-13 too. See our EAN-13 guide.
- Get a GS1 company prefix. Join GS1 US or your country's GS1 organisation.
- Assign a number to each product. One per product, size and colour.
- Make the UPC-A. Type the first 11 digits; the generator adds the check digit.
- Print at 80% to 200% and test. Scan the proof with a till scanner or a scanner app.