How to calculate a check digit manually
| ID Key Format | Digit positions | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| GTIN-8 | N1 | N2 | N3 | N4 | N5 | N6 | N7 | N8 | ||||||||||
| GTIN-12 | N1 | N2 | N3 | N4 | N5 | N6 | N7 | N8 | N9 | N10 | N11 | N12 | ||||||
| GTIN-13 | N1 | N2 | N3 | N4 | N5 | N6 | N7 | N8 | N9 | N10 | N11 | N12 | N13 | |||||
| GTIN-14 | N1 | N2 | N3 | N4 | N5 | N6 | N7 | N8 | N9 | N10 | N11 | N12 | N13 | N14 | ||||
| GSIN | N1 | N2 | N3 | N4 | N5 | N6 | N7 | N8 | N9 | N10 | N11 | N12 | N13 | N14 | N15 | N16 | N17 | |
| SSCC | N1 | N2 | N3 | N4 | N5 | N6 | N7 | N8 | N9 | N10 | N11 | N12 | N13 | N14 | N15 | N16 | N17 | N18 |
| Step 1: Multiply value of each position by | ||||||||||||||||||
| x3 | x1 | x3 | x1 | x3 | x1 | x3 | x1 | x3 | x1 | x3 | x1 | x3 | x1 | x3 | x1 | x3 | ||
| Step 2: Add results together to create sum | ||||||||||||||||||
| Step 3: Subtract the sum from nearest equal or higher multiple of ten = Check Digit | ||||||||||||||||||
The following table gives an example to illustrate how a GTIN-13 Check Digit is calculated:
| ID Key Format | N1 | N2 | N3 | N4 | N5 | N6 | N7 | N8 | N9 | N10 | N11 | N12 | N13 | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Number without Check Digit | 6 | 2 | 9 | 1 | 0 | 4 | 1 | 5 | 0 | 0 | 2 | 1 | - | |||||
| Step 1: Multiply | x | x | x | x | x | x | x | x | x | x | x | x | - | |||||
| by | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | - | |||||
| Step 2: Add results | = | = | = | = | = | = | = | = | = | = | = | = | - | |||||
| to create sum | 6 | 6 | 9 | 3 | 0 | 12 | 1 | 15 | 0 | 0 | 2 | 3 | =57 | |||||
| Step 3: Subtract the sum from nearest equal or higher multiple of ten = 60- 57 = 3 (Check Digit) | ||||||||||||||||||
| Number with Check Digit | 6 | 2 | 9 | 1 | 0 | 4 | 1 | 5 | 0 | 0 | 2 | 1 | 3 | |||||