How to calculate check number?

General discussion about Morovia barcode fonts, OCR/MICR fonts and postal fonts.

How to calculate check number?

Postby Gleb K on Tue Jun 07, 2022 4:11 am

I need to create a barcode for a product sold by weight. I use Loyverse POS and they have a manual how to make a number. The only unclear moment is how to find the check number (the last digit in the code).

There is a way to do it manually and there are websites. with calculators.

When I calculate the bar code manually I gat one number. When I use the calculator it's another.

For example if my barcode is as below.


Where 02 is EAN13

10100 is the SKU

00001 is weight (as we sell by grams. It's soap to make it clear). Stands for 00 kg 001 gr

X is the check sum.

I followed the instruction below:

If I calculate manually following the guide from the link.

1. Sum all the digits in even positions and multiply by 3. I only have 2 multiplied by 3 = 6

2. Add all the the digits in odd positions (except for the last one which is check digit - I don't even have check digit yet. This is what I am trying to figure out. Why even to mention this. ) to the number you’ve got. OK. I got 3 (sum of all 1s)

3. Divide that number by 10 and take the reminder (I believe the number 3, right?) 3/10 = 0.3

4. If the reminder is not 0, subtract it from 10. 10-0.3 = 9.7

Obviously there is something wrong I am doing here or I understand it wrong.

If I put this number 021010000001 in the calculator it gives me 9 but I put 12 digits because I don't have the check number because this is what I am trying to calculate. The example in the calculator has 13 digits.

Please help.
Gleb K
Posts: 2
Joined: Tue Jun 07, 2022 4:04 am

Re: How to calculate check number?

Postby glitch on Tue Jun 07, 2022 8:54 am

You can use

Mod10 check digit algorithm is the same for UPC-A and EAN-13. You start from the right most digit, assign odd/even position to each digit. Then sum all digits, divide by 10. The remainder is the check digit.
The information above is provided "AS IS", with no warranties, and confers no rights.
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Support Engineer
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Re: How to calculate check number?

Postby Gleb K on Wed Jun 08, 2022 4:04 am

Thank you.

I will try. To clarify for EAN 13 I need to put 12 digits as 13th is the check number which I need to calculate.

Do I get it right?

It gives me 9

But if I calculate it manually I get another number as in the first message
Gleb K
Posts: 2
Joined: Tue Jun 07, 2022 4:04 am

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