About the Check Digit Calculator
The last digit of a product barcode is a check digit, which lets scanners detect misreads and typos. It is calculated from the other digits using the GS1 method. This tool finds the check digit for a code you give without it and tells you the full code and its type, or verifies a complete code. It works for EAN-8, UPC-A, EAN-13, GTIN-14 and 18-digit SSCC codes. Type a barcode without its last digit, or a full code and the barcode check digit appears at once, with a few related figures underneath, and you can copy the result with one tap. The sums run in your browser, so nothing you enter is uploaded.
Updated October 2026
How to use the Check Digit Calculator
- 1Enter a barcode without its last digit, or a full code.
- 2Pick the units or options from the menus if the barcode check digit tool offers them.
- 3Read the barcode check digit in the large result box.
- 4Look at the extra rows for related figures.
- 5Press Copy result to keep the answer.
When you need the barcode check digit
Shopkeepers, product managers and developers use it when they create their own barcodes, check a spreadsheet of product numbers or find a typing mistake in an inventory list. It is also a way to understand how barcodes protect against errors.
A valid check digit does not mean that the code is registered to a product; only GS1 or the registry can tell. For your own internal numbers, prefixes beginning with 2 are reserved for private use in many shops.
How the barcode check digit is worked out
From the right, multiply the digits alternately by 3 and 1 and add them up. The check digit is the number that brings the total up to the next multiple of 10. For the EAN-13 code body 400638133393, the sum gives a check digit of 1, so the full code is 4006381333931. The UPC-A body 03600029145 gives 2. The EAN-8 body 9638507 gives 4, making 96385074.
Every answer on this page comes from that one rule, so you can check any result by hand with a calculator. The figures shown underneath, such as other units, are conversions of the same answer.
- Five code types
- Calculate or verify
- Full code shown
Mistakes to avoid with barcode check digit
Count the digits carefully. A 12-digit body gives an EAN-13, an 11-digit body a UPC-A. The check digit is the last digit of the complete code. This tool does not draw barcodes; use the Barcode Generator for that.
On phone and computer
On a phone, type into the boxes one after another and read the barcode check digit underneath; Copy result puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the barcode check digit move. The check digit calculator works the same on both. To check a card or ID number, use the Luhn Validator, and the ISBN Converter handles book numbers.
Features
- 12 digits make EAN-13
- UPC-A is EAN-13 with a leading 0
- Valid does not mean registered
- Clear messages when the barcode check digit inputs make no sense
- Copy the result with one tap
- Private: nothing is uploaded
Frequently asked questions
How do I calculate barcode check digit?
From the right, multiply the digits alternately by 3 and 1 and add them up. The check digit is the number that brings the total up to the next multiple of 10. For the EAN-13 code body 400638133393, the sum gives a check digit of 1, so the full code is 4006381333931. The UPC-A body 03600029145 gives 2. The EAN-8 body 9638507 gives 4, making 96385074.
What is the formula for barcode check digit?
From the right, multiply the digits alternately by 3 and 1 and add them up. The check digit is the number that brings the total up to the next multiple of 10. The check digit calculator applies it exactly and rounds only the displayed answer to six significant figures.
How is the EAN-13 check digit calculated?
Multiply the digits alternately by 1 and 3 starting from the left of the 12-digit body, add them up, and take the amount needed to reach a multiple of 10.
Is a UPC-A the same as an EAN-13?
A UPC-A is an EAN-13 with a leading zero.
Who assigns barcodes?
GS1 and its national member organisations.
Is this check digit calculator free and private?
Yes. It is free, needs no account and runs in your browser, so the numbers you type are not uploaded or stored.