Validation of UPC and EAN Barcode Numbers

All UPCs are 12-digit numbers, but not every 12-digit number is a valid UPC.

How so? Because every UPC has what's called a "check digit". This check digit — the last digit in every UPC — helps to catch errors like typos and provide some degree of confidence that you're actually dealing with a UPC.

EAN codes are similar. Though they have 13 digits, they too have a final check digit to help weed out errors.

Just because it validates...

...doesn't mean that it is an active UPC!

That's right; a lot of 12-digit (and 13-digit) numbers will “validate” as a UPC (or EAN), but that doesn't mean the code has actually been assigned to a product. That said, if it validates the number could be assigned in the future, so it may wind up on a product someday.

If you're wondering what product a particular number is associated with — if any — you can always plug it into our search form to check against our database of millions of UPCs.

How UPC Validation Works — An Example

Let's break down the logic for validating a UPC. For an example, we'll use the code 829576019311. One (1) is the check digit in this case.

With the following 5 steps we will confirm this UPC is valid:

Take all of the odd-position digits — the 1st, 3rd, 5th, 7th, 9th, and 11th digits — and add them together.
```
8 + 9 + 7 + 0 + 9 + 1 = 34
```
Multiply the result of step 1 (34) by the number 3.
```
34 * 3 = 102
```
Now, take all of the even-position digits (positions 2, 4, 6, 8 and 10), and add them together.
```
2 + 5 + 6 + 1 + 3 = 17
```
Take the sum of the results from steps 2 and 3.
```
102 + 17 = 119
```
The check digit is calculated by figuring out what number needs to be added to the result of step 4 in order to make it a multiple of 10.
```
119 + 1 = 120
```

Therefore, the check digit for this UPC barcode is 1.

Example EAN Validation

Validating an EAN is very similar; we're just dealing with one additional digit. For this example, we'll use the code 5900049003619.

Here are the 5 steps to validate this EAN code:

Take all of the odd-position digits (exluding position 13, since this last number is the check digit), and add them together.
```
5 + 0 + 0 + 9 + 0 + 6 = 20
```
Now, take all of the even-position digits (positions 2, 4, 6, 8, 10, and 12), and add them together.
```
9 + 0 + 4 + 0 + 3 + 1 = 17
```
Multiply the result of step 2 (17) by the number 3.
```
17 * 3 = 51
```
Take the sum of the results from steps 1 and 3.
```
20 + 51 = 71
```
The check digit is calculated by figuring out what number needs to be added to the result of step 4 in order to make it a multiple of 10.
```
71 + 9 = 80
```

Therefore, the check digit for this EAN barcode is 9, and we confirm that 5900049003619 is a valid EAN.