GTIN
Global Trade Item Number
What is a GTIN?
A Global Trade Item Number (GTIN) is a GS1 identification key used to uniquely identify trade items - any product or service that may be priced, ordered, or invoiced at any point in the supply chain. GTINs are the numbers encoded in the barcodes you see on virtually every retail product worldwide.
A GTIN identifies a type of product, not an individual unit. Every can of the same soft drink in the same size carries the same GTIN. To identify a specific individual item, EPC schemes like SGTIN-96 and SGTIN-198 combine a GTIN with a unique serial number.
Used for: Retail point-of-sale, inventory management, supply chain logistics, product catalogues, and as the base identifier encoded into SGTIN EPC tags on RFID chips.
GTIN formats
GS1 defines four GTIN formats. They all serve the same purpose - identifying a trade item - but differ in length and application. Shorter formats can always be expressed as GTIN-14 by left-padding with zeros.
| Format | Digits | Barcode | Typical use |
|---|---|---|---|
| GTIN-8 | 8 | EAN-8 | Very small products where a full barcode won't fit |
| GTIN-12 | 12 | UPC-A | Retail products in North America |
| GTIN-13 | 13 | EAN-13 | Retail products worldwide (most common format globally) |
| GTIN-14 | 14 | ITF-14, GS1-128 | Cases, cartons, and pallets - adds an indicator digit to a GTIN-13 |
When you hear "UPC" in the US or "EAN" in Europe, these are barcode symbologies that encode GTINs. The underlying number is always a GTIN.
GTIN structure
Every GTIN is built from three components. The boundary between the company prefix and item reference varies - GS1 assigns company prefixes of different lengths depending on how many product numbers a company needs.
| Component | Description |
|---|---|
| GS1 Company Prefix | A variable-length number (6 to 12 digits) assigned to a company by their local GS1 Member Organisation. Identifies who owns the number. |
| Item Reference | Assigned by the brand owner to identify a specific product within their prefix. The number of available digits depends on the length of the company prefix. |
| Check Digit | A single digit calculated using the mod-10 algorithm. Catches scanning and transcription errors. |
For GTIN-14 specifically, a leading indicator digit (1-9) precedes the company prefix. It identifies the packaging level - for example, indicator 1 might be a case of 12 units, while 2 could be a case of 24. Indicator 0 means this is the base unit (equivalent to the GTIN-13).
Example: GTIN-13
0614141123452Check digit calculation
The last digit of every GTIN is a check digit computed using the GS1 mod-10 algorithm. It detects single-digit errors and adjacent transpositions - the most common mistakes when numbers are typed or scanned.
- Number the positions from right to left, starting at position 1 (the check digit itself). Working right to left, assign multipliers alternating
1and3starting with1at position 1. - Multiply each digit (except the check digit) by its multiplier. Equivalently: starting from the rightmost digit before the check digit, multiply alternate digits by 3 and 1.
- Sum all the products.
- Check digit = (10 - (sum mod 10)) mod 10. This is the smallest number that, added to the sum, produces a multiple of 10.
Worked example: 061414112345
| Digit | 0 | 6 | 1 | 4 | 1 | 4 | 1 | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Multiplier | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 |
| Product | 0 | 18 | 1 | 12 | 1 | 12 | 1 | 3 | 2 | 9 | 4 | 15 |
Sum = 0 + 18 + 1 + 12 + 1 + 12 + 1 + 3 + 2 + 9 + 4 + 15 = 78.
Check digit = (10 - (78 mod 10)) mod 10 = (10 - 8) mod 10 = 2.
Full GTIN-13: 0614141123452.
How GTIN relates to EPC
A GTIN identifies a product type. An EPC identifies a specific individual item. The SGTIN (Serialised GTIN) EPC scheme bridges the two by encoding a GTIN together with a unique serial number.
When encoding a GTIN into SGTIN, the GTIN is broken apart and reassembled:
- The GTIN is zero-padded to 14 digits (GTIN-14 form).
- The check digit is dropped - it is not stored in the EPC because it can always be recalculated.
- The first digit (the indicator digit) is moved: it becomes the most significant digit of the item reference field in the SGTIN.
- The GS1 Company Prefix is encoded in the company prefix field, and the remaining item reference digits (indicator + original item reference) go into the item reference field.
- A serial number is appended - numeric only in SGTIN-96 (up to 38 bits), or alphanumeric in SGTIN-198 (up to 140 bits).
Example mapping
| Layer | Value |
|---|---|
| GTIN-13 | 0614141123452 |
| GTIN-14 (zero-padded) | 00614141123452 |
| Indicator | 0 (first digit of GTIN-14) |
| Company Prefix | 0614141 |
| Item Reference (in SGTIN) | 012345 (indicator 0 + reference 12345) |
| Serial Number | 6789 (assigned per individual item) |
| Pure Identity URI | urn:epc:id:sgtin:0614141.012345.6789 |
How to look up a GTIN
GS1 operates Verified by GS1, a global registry where you can look up product information by entering a full GTIN. The service returns the brand owner, product description, and other attributes - provided the brand owner has published their data.
You need the complete GTIN including the check digit to perform a lookup. If you have an EPC, you must first decode it back to a GTIN (re-insert the indicator digit into the correct position and recalculate the check digit) before searching.
Related EPC schemes
Source
GS1 GTIN Standards and the GS1 General Specifications. The GTIN-to-SGTIN encoding procedure is defined in the GS1 EPC Tag Data Standard, Release 2.3, Section 10. Read the EPC encoding guide for a full worked example of decoding hex to URI.