GTIN Check Digit Calculator: EAN-13 & UPC
GS1 check digits use alternating weights of 3 and 1, starting at the rightmost body digit. Add the weighted digits and choose the digit that brings the sum to a multiple of 10. The 12-digit body 400638133393 needs check digit 1. Calculate a digit or validate a GTIN-8, GTIN-12, GTIN-13 or GTIN-14 without sending the number anywhere.
GS1 check digit
1
Show breakdown
Calculation breakdown
- Check digit
- 1
| Check digit | 1 |
|---|
GS1 check digits do not allocate a globally unique barcode. Use a company prefix licensed to your organisation. Code 128 can encode your internal SKU without a GS1 allocation.
At a glance
- SKU scheme
- fixed prefix + attribute codes + zero-padded sequence, hyphen separated, 8 to 16 characters
- EAN-13 (GTIN-13)
- GS1 company prefix + item reference + check digit; Australian prefixes start 930 to 939
- Check digit
- multiply digits from the right by 3, 1, 3, 1…, sum, round up to the next 10
- GTIN-14 for cartons
- packaging indicator + GTIN-13 body + new check digit
- Labels
- Avery L7160 (21 a sheet), L7163 (14), L7651 (65) or 100 × 150 thermal
- Note
- Exports in Odoo and MYOB Acumatica product import layouts
How it is calculated
Generate the cross product of attributes in segment order, assign sequence numbers and test for duplicate codes. Calculate a GS1 check digit with alternating weights of three and one.
SKU count = product of attribute value counts
GTIN check digit = (10 − weighted digit sum mod 10) mod 10- Rates as at 2026-09-07 from Gs1
- Rates as at 2026-09-07 from Label Sheets: Avery Australia templates · Verification pending
Does a correct GTIN check digit prove ownership?
No. A check digit confirms that the number satisfies the GS1 arithmetic rule. It does not establish who assigned the number or whether your business may use it. Obtain the appropriate GS1 allocation and keep assignment records for products and packaging levels.
How many digits should I enter to calculate a check digit?
Enter the body without the last digit: seven digits for GTIN-8, eleven for GTIN-12, twelve for GTIN-13 or thirteen for GTIN-14. To validate an existing number, enter the complete code including its check digit and preserve any initial zeroes.
How should you structure a SKU?
Keep it short, unique and consistent. Start with a fixed segment for the product family, add one segment per attribute that changes stock (colour, size, pack), and finish with a zero-padded sequence so two products can never collide. Use uppercase letters and digits only, separate segments with a hyphen, avoid letters that look like digits (O and 0, I and 1), and keep the whole thing under about sixteen characters so it fits on a label and a pick list. Do not encode price, supplier or location, because those change and the SKU must not. TS-BLK-M-002 says everything a picker needs; a SKU that is the supplier’s part number says nothing when you change supplier.
What is the difference between a SKU and a barcode?
A SKU is your internal identifier; you invent it and it is unique inside your business. A barcode number (a GTIN, printed as an EAN-13 in Australia) is a global identifier issued under a GS1 company prefix so a product scans the same at your warehouse, your customer’s warehouse and a retail checkout. A product has one SKU and may have one GTIN per sellable unit and another for the carton (a GTIN-14). Internal-only items such as bins, locations and bulk stock can be barcoded with a Code 128 of the SKU itself, which needs no GS1 membership.
How do you calculate an EAN-13 check digit?
Take the first twelve digits. Starting from the rightmost, multiply the digits alternately by 3 and 1 and add the results. The check digit is the number that brings that sum up to the next multiple of ten (zero if it already is one). For 400638133393 the sum is 89, so the check digit is 1 and the barcode is 4006381333931. The same rule applies to GTIN-8, UPC-A and GTIN-14. The calculator on this page does it for one code or a list, and validates codes you already have; a wrong check digit is the most common reason a barcode “will not scan” into an ERP.
How do SKUs and barcodes get into an ERP?
Every product record carries the SKU as its code and the GTIN in the barcode field, and variants carry their own of each. Export the list from this page in the Odoo layout (internal reference, name, attribute columns, barcode) or the MYOB Acumatica layout (inventory ID, description, attributes, alternate ID) and it loads through the standard import. Getting the scheme right before the import is the point: renaming SKUs after transactions exist is painful in any system, and matrix items in MYOB Acumatica generate the child SKUs from the scheme you define once.
| Position | SKU | Colour | Size | EAN-13 (prefix 93001) |
|---|---|---|---|---|
| 1 | TS-BLK-S-001 | Black | S | 9300100001 + item + check (generated) |
| 2 | TS-BLK-M-002 | Black | M | |
| 5 | TS-WHT-S-005 | White | S | |
| 12 | TS-NVY-XL-012 | Navy | XL | |
| Check digit example | 400638133393 → 1 | 4006381333931 | ||
| Scheme summary | 12 SKUs, 13 characters, no duplicates |
Frequently asked questions
Does a correct GTIN check digit prove ownership?
No. A check digit confirms that the number satisfies the GS1 arithmetic rule. It does not establish who assigned the number or whether your business may use it. Obtain the appropriate GS1 allocation and keep assignment records for products and packaging levels.
How many digits should I enter to calculate a check digit?
Enter the body without the last digit: seven digits for GTIN-8, eleven for GTIN-12, twelve for GTIN-13 or thirteen for GTIN-14. To validate an existing number, enter the complete code including its check digit and preserve any initial zeroes.
Do I need a GS1 membership to make barcodes?
Only for barcodes that will be scanned outside your business, such as products sold through retailers or marketplaces, which need a GTIN under a GS1 Australia company prefix. For internal use, a Code 128 barcode of your own SKU works with any scanner and any ERP and costs nothing. This tool generates both.
How long should a SKU be?
Between 8 and 16 characters is the practical range: long enough to carry the family, the attributes and a sequence, short enough to print on a small label and read on a pick list. Some systems cap the code length (MYOB Acumatica's inventory ID defaults to 30, Odoo has no fixed limit); the generator shows the maximum length of the set.
ERP for wholesale distribution in Australia
Getting the SKU scheme right is the first week of every ERP project we run. If you are about to import a catalogue, talk to us before you do.
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