Carton barcode vs unit barcode: make the code for your outer box

The unit barcode (an EAN-13) scans at the shop till and rings up one item. The carton barcode (an ITF-14) scans at the warehouse and books the whole box, and you build it from your unit number with a new front digit and a new check digit.

Carton barcode vs unit barcode: two codes, two scanners

Your product has one barcode on the pack. That is the unit barcode, an EAN-13. It scans at a till and rings up one item at its MRP.

When you ship 12 of those packs in a brown box, the box needs its own code. That is the carton barcode. The usual form is an ITF-14, a wide, heavy barcode that prints well on corrugated board.

The carton barcode vs unit barcode question comes down to who holds the scanner. The cashier scans the unit. The person at the receiving dock scans the carton. Each scan tells a different system a different count.

Who scans which

The till in a shop reads the EAN-13 on the single pack. One beep, one item, one line on the bill.

A distributor, a warehouse or the back room of a larger store reads the ITF-14 on the outer box. One beep there means one carton of 12, or 24, or whatever count you packed. Stock goes up by the full count and nobody has to open the box.

A shopper never sees the carton code. A cashier never needs it. Keep the two apart and both scanners do their job.

Why the unit code must not show on the outer box

Many first-time sellers print the unit barcode on the carton too. It looks tidy. It causes trouble.

A receiving scanner that reads the unit code on a box of 12 books one item. Your buyer's stock is now short by 11. The next order is placed on a wrong count, and someone ends up counting by hand.

If you pack units in clear shrink wrap and the unit codes show through, turn the packs so the codes face inward, or wrap the bundle in an opaque sleeve. The only code a scanner should find on the outside is the carton code.

How the ITF-14 is built from your EAN-13

The carton code is built from the unit number you already have. It has 14 digits, in three parts:

1. An indicator digit at the front, from 1 to 8. It marks the pack level.
2. The first 12 digits of your EAN-13, in the same order. Leave off its last digit.
3. A new check digit at the end, worked out again from the 13 digits before it.

The last step is where people slip. You cannot just put a 1 in front of your unit number. The check digit changes, and a scanner will not read a code with the wrong one.

The sum is short. Take the 13 digits before the check digit. Starting from the right, multiply them by 3, then 1, then 3, then 1, and so on to the left. Add all the results. The check digit is the amount you need to add to reach the next round ten. If the total is already a round ten, the check digit is 0. A free check digit calculator does the same sum, and it is worth running both once to be sure.

Each pack size gets its own indicator. A box of 12 might use indicator 1. A box of 24 of the same product uses indicator 2. A shrink-wrapped tray of 6 inside that box of 24 can use indicator 3. Write the choices in one sheet, with the count beside each, so nobody reuses a digit for a different count later.

A mixed box, with two or more different products inside, cannot be built this way. It needs a number of its own. Tell us where you sell and what goes in the box, and we will help you plan it.

If you do not have a unit number for the product yet, start with one from PurchaseBarcode. Use code STARTUP10 for 10% off one order per account. It is valid until 31 December 2026 or for the first 100 uses on this site, whichever comes first.

Sizing and printing the carton code

Corrugated board is soft and the ink spreads. That is why the ITF-14 uses wide bars and a thick frame around the whole code, called a bearer bar. The frame keeps the printing plate pressing evenly, and it stops a scanner from reading only part of the code.

At full size the code, with its clear space on both sides, is a little over 150 mm wide. The bars stand 32 mm tall. On brown board printed straight from a plate, stay close to full size and make the bearer bar about 5 mm thick. On a smooth white label you can go somewhat smaller, but there is rarely a reason to.

Keep at least 10 mm clear to the left and right of the bars. No text, no box lines and no edge of the label in that space.

Print black bars on white or brown. Do not print the bars in red, orange or yellow. Most scanners read those colours as blank.

If you use stick-on labels instead of printing on the board, a 100 mm by 150 mm thermal label is the common choice. Set it in landscape and the ITF-14 fits near full size, with room under it for the product name and count.

Where it goes on the box

Put the carton code on at least two sides that meet at a corner, usually one long side and one short side. A box on a shelf or a pallet can then be scanned whichever way it faces.

Place the bottom of the bars about 32 mm up from the base of the box. Keep the code at least 19 mm in from any upright edge, so it does not bend round a corner. Keep it off flaps, seams and anywhere the packing tape will run.

Next to the code, print the product name and the count in plain words, such as 12 x 500 ml. Staff read that line when the scanner is out of reach, and it lets them spot a box packed with the wrong count.

Make your first carton code today

Take your product's EAN-13 and the number of units in your box. Pick the indicator digit for that count from your sheet. Write the first 12 digits of the unit number after it. Work out the new check digit with the sum above.

Put the 14 digits into any ITF-14 barcode generator and turn the bearer bar on. Print one test label at full size. Stick it on two touching sides of a real packed box, at the height above.

Scan it with a handheld reader or a phone scanning app. The scan should show 14 digits that match your sheet exactly. Then scan one unit pack from inside the box and check it shows the unit number, not the carton number. When both scans match, the label file is ready for your printer, and every box from this batch can go out with it.

If a buyer asks for carton labels in a layout of their own, tell us where you sell and send us their sheet. We will help you match it.