GTIN-14 and ITF-14: how to build a carton barcode from a UPC or EAN

What a GTIN-14 is (and why it has so many names)

A GTIN-14 is the number that identifies a case containing several units of the same product: the carton in which 6, 12 or 24 jars ship to a distributor. You will see it under several names that, in practice, mean the same thing:

• GTIN-14: the official name of the 14-digit number in the GS1 system.
• ITF-14: not the number but the barcode symbology (Interleaved 2 of 5) used to draw it. It is the one with a frame around it.
• EAN-14 and DUN-14 (Distribution Unit Number): older or informal names, still common among distributors and in Europe.
• Case code, carton code, shipping container code: what warehouses and retailers usually call it.

If a customer asks for “the ITF-14 of the case”, they are asking for the case's GTIN-14, drawn as an ITF-14 barcode.

The key idea: it is built from the unit's UPC or EAN

The case number is not made up: it derives from the UPC-A or EAN-13 of the product inside. It keeps the same company and item numbers, with two changes: a new digit at the front and a recalculated check digit at the end.

The indicator digit tells packaging levels apart for the same product. A common convention is 1 for the first case size, 2 for a larger case or a different pack, and so on up to 8. Each indicator must stand for one single pack configuration: if 1 is the 12-unit case, it cannot also be the 24-unit one.

How to calculate it step by step

Take the UPC-A 036000291452 and say you want the code for a case of 12.

1. Pad the UPC-A to 13 digits with a leading zero: 0036000291452. (If you start from an EAN-13, skip this step.)
2. Drop the check digit (the last one, 2). That leaves 12 digits: 003600029145.
3. Add the indicator in front. If this case is level 1: 1003600029145 (13 digits).
4. Calculate the check digit with the usual GS1 modulo-10 algorithm: number the digits from the right, multiply alternately by 3 and by 1, add them up and find what is missing to reach the next multiple of ten.

The sum is 15 + 4 + 3 + 9 + 6 + 0 + 0 + 0 + 18 + 3 + 0 + 0 + 3 = 61. To reach 70 you need 9, so the complete code is 10036000291459.

With other indicators, the same product gives different codes. Notice that the check digit changes even though the rest of the number is the same:

If you already have a GTIN-14 and want to validate it, multiply its 14 digits alternately by 3 and 1, starting with 3 on the first digit (because 14 is even), and add them: the total must be a multiple of 10. With 10036000291459 the sum is 70. The basics of the calculation are explained in the check digit guide.

Two very common mistakes

• Keeping the unit's check digit. Someone who adds a 1 in front and leaves the 2 at the end gets 10036000291452, a 14-digit number whose check digit does not add up. You must remove the last digit and recalculate it.
• Using the same number for different cases. A case of 6 and a case of 12 of the same product need different indicators. If both carry the same code, your customer's warehouse cannot tell them apart.

What if the case mixes different products?

A GTIN-14 describes a case of one single product. A case with several different products (a variety pack with three flavors) cannot be derived from the code of any of its components: it needs its own identifier, assigned as one more item number of your company. If you are unsure how to encode it, ask your customer or your GS1 member organization: it affects how their system will read it.

Do I need an official UPC or EAN to have a GTIN-14?

For the code to be valid in another company's logistics, yes: it is built with your own company prefix, the one GS1 assigns to you. If the unit's code is not yours, the case code you derive will not be yours either and may collide with another company's. In the guide on how to get official UPC and EAN barcodes we explain the process and what to do if you only need codes for your own use.

For goods that never leave your business (your own warehouse, archive boxes) you need neither: a Code 128 with your own reference is more flexible.

How it is drawn: ITF-14

The number is encoded as ITF-14 (Interleaved 2 of 5), a symbology that packs digits in pairs: the bars encode the first digit of each pair and the spaces the second. That is why it only accepts an even number of digits, and 14 qualifies. It also has a frame (bearer bars) that protects the edge bars and helps when printing on rough surfaces such as corrugated cardboard.

The GS1 General Specifications give these approximate figures for ITF-14:

With the minimum module of 0.495 mm, the code is about 67 mm (2.6 in) wide without the quiet zones (about 77 mm with them); at the nominal 1.016 mm module, about 137 mm (5.4 in), or 157 mm with them. That is a lot for a small label, and it is why ITF-14 is printed on large labels (for example 4 × 6 in on a thermal roll) or directly on the carton.

If you print directly on corrugated cardboard with a plate-based process (flexo), carton and printing guidelines usually recommend a thicker module, around 0.635 mm or more. Confirm with your printer.

How to do it with GeneraEtiquetas

The tool above is set up with this article's example, 10036000291459, as an ITF-14:

1. Type the first 13 digits (indicator + 12 digits of the padded unit code) and the tool calculates and appends the check digit. Or paste all 14 and it validates the last one.
2. With a list of cases, paste it from Excel in “Many labels” mode and generate them all at once. To prepare the list, see barcodes from Excel.
3. Choose a large label in step 3. The tool warns you if the bars come out too thin or too short: for ITF-14 it treats a module under 0.5 mm or a height under 20 mm as “tight”.
4. Print a test and scan it with the real scanner at your warehouse or your customer's before printing the whole run.

If you need extra logistics information on the same label (lot number, expiry date, pallet number), the usual standard is GS1-128, an application of Code 128 that this tool does not generate. In that case, ask your customer or carrier which format they require. And to see when each code type fits, read which barcode type to use.

How we check the quality of the codes the tool generates is explained in How we verify measurements and codes.