Free check digit calculator and GTIN converter
Every UPC, EAN, GTIN-14 and SSCC ends in a check digit calculated from the digits before it. Calculate a missing one, catch a typo before it reaches a print run, and convert a number between its UPC-E, UPC-A, EAN-13 and 14-digit forms.
- Free to use
- No sign-up
- No watermark
- Personal and commercial use
- Runs in your browser
Calculate or verify a check digit
Type a number without its check digit to calculate it, or a complete number to validate it.
- As a GTIN-12 (UPC-A) without its check digit, the check digit is 5
012345678905
Show the math
Weights alternate 3, 1, 3, 1… starting from the rightmost digit before the check digit. Add the products, then find what brings the sum up to the next multiple of 10.
| Digit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Weight | ×3 | ×1 | ×3 | ×1 | ×3 | ×1 | ×3 | ×1 | ×3 | ×1 | ×3 |
| Product | 0 | 1 | 6 | 3 | 12 | 5 | 18 | 7 | 24 | 9 | 0 |
Sum = 85. Next multiple of 10 = 90. Check digit = 5.
Convert UPC-E, UPC-A, EAN-13 and GTIN-14
Read as UPC-A without check digit; check digit 4 added.
- UPC-A (GTIN-12)
042100005264 - UPC-E (zero-suppressed)
04252614 - EAN-13 (GTIN-13)
0042100005264 - GTIN-14 (14-digit form for databases)
00042100005264
These are the same number written at different lengths with leading zeros — not new numbers. A GTIN-14 with an indicator digit other than 0 identifies a case or pack and must be assigned, not converted.
How the calculation works
GS1 numbers all use the same modulo-10 method. Starting from the rightmost digit before the check digit, multiply the digits alternately by 3 and 1, add the results, and pick the digit that brings the total up to the next multiple of 10. Open “Show the math” above to see every step for your number. The check digit guide works through a UPC-A and an EAN-13 by hand and explains which mistakes the method catches.
Which lengths this calculator understands
| Digits with check digit | Key | Where you see it |
|---|---|---|
| 8 | GTIN-8 | EAN-8 barcodes on very small packages |
| 12 | GTIN-12 | UPC-A barcodes (and UPC-E, which compresses some of them) |
| 13 | GTIN-13 | EAN-13 barcodes |
| 14 | GTIN-14 | ITF-14 and GS1-128 barcodes on cases and cartons |
| 17 | GSIN | Shipment identification |
| 18 | SSCC | Pallet and parcel labels (GS1-128, AI 00) |
Some lengths are ambiguous. Twelve digits can be a complete UPC-A or an EAN-13 missing its check digit, so the calculator shows both readings.
A correct check digit is not a licensed number
The check digit only shows that the digits are internally consistent. It says nothing about who the number belongs to. For products sold at retail, the company prefix inside the number must be licensed to your business. See how to get UPC barcodes and what a GTIN is.
About the conversions
A UPC-A, its EAN-13 with a leading zero, and its 14-digit form with two leading zeros are the same GTIN written at different lengths. Databases often store the 14-digit form. UPC-E is a shortened way to print certain UPC-A numbers that contain runs of zeros, and only some numbers can be shortened. A GTIN-14 that starts with an indicator digit other than 0 identifies a different packaging level, so it has to be assigned, not converted. See when you need a new GTIN.