## Check Digit Calculator

What is a Check Digit and a Check Digit Calculator?

The last digit of all numeric fixed-length GS1 Identification (ID) Keys is a check digit, which is required and ensures the integrity of the key. The last digit, being the check digit, is calculated using a simple algorithm based on the preceding numbers in the key. The result is an accurately constructed and scannable barcode.

This page provides information for each GS1 ID Key, shows how the calculator works and even provides you step by step instructions on how to manually calculate the check digit by using the simple algorithm, should the need arise.

### Global Trade Item Number (GTIN) Check Digit Calculator

ID Key Format

Item Reference
(without check digit)

Check
Digit

GTIN
Format

GTIN-8
(Enter 7 digits)
GTIN-12
(Enter 11 digits)
GTIN-13
(Enter 12 digits)
GTIN-14
(Enter 13 digits)

### Serial Shipping Container Code (SSCC) Check Digit Calculator

ID Key Format

Item Reference
(without check digit)

Check
Digit

SSCC
Format

SSCC
(Enter 17 digits)

### Global Location Number (GLN) Check Digit Calculator

ID Key Format

Location Reference
(without check digit)

Check
Digit

GLN
Format

GLN
(Enter 12 digits)

### How does the check digit calculator work?

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

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 sum from the next highest multiple of ten = Check digit

### How to manually calculate the check digit?

Positions

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

-

=

=

=

=

=

=

=

=

=

=

=

=

-

to create sum

6

6

9

3

0

12

1

15

0

0

2

3

= 57

Step 3: Subtract sum from next highest 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