Box styles4 min readUpdated Nov 13, 2026

Folding cartons

A folding carton is the printed box you take off a shop shelf. It starts as one flat sheet of board, cut and creased, and reaches the packer folded flat. What sets one style apart from another is mostly how its two ends close.

One sheet, glued once

On the dieline of most folding cartons you see four panels in a row, a narrow glue flapGlue flap A narrow flap at the end of the row of panels that the box maker glues to the last panel, turning the sheet into a tube. at one end and flaps above and below the panels. The box maker glues the glue flap to the last panel, so the carton becomes a flat tube. Flat tubes stack and ship in little space. At the packing table someone squares the tube up, closes one end, puts the product in and closes the other.

Most folding cartons are paperboard, usually 300–400 g, about 0.4–0.6 mm thick. A larger or heavier carton can go up to a thin corrugated board such as F or E flute. Small cartons stay with paperboard: corrugated makers set a minimum size for a tuck box, often around 76 × 38 × 51 mm. Our tuck box and crash lock bottom box take board up to 2 mm; the snap lock bottom box goes up to 7 mm.

Tuck end: straight or reverse

On a tuck box each end closes with a flap that tucks in. Two small dust flapsDust flap A small flap on a side panel of a tuck box that folds in first, under the closure flap, and keeps the tuck in place. on the side panels fold in first, under the closure flap. The tuck has a short slit at each side, so it catches behind the dust flaps and stays shut.

• Straight tuck end (STEStraight tuck end (STE) A tuck box whose top and bottom closure flaps both hang on the back panel, so the two ends open the same way., ECMA A20.20.03.03): both closure flaps hang on the back panel, so the two ends open the same way.
• Reverse tuck end (RTEReverse tuck end (RTE) A tuck box whose top flap hangs on the back panel and bottom flap on the front, so the ends open in opposite directions., ECMA A20.20.03.01): the top flap hangs on the back panel and the bottom flap on the front, so the ends open in opposite directions. In the editor it is the Reverse tuck switch.

You will often read that a reverse tuck fits more boxes on a press sheet. Sometimes it does, sometimes the straight one wins: it depends on the size and the sheet. A tuck end is happiest with light products, such as a tube of cream, a deck of cards or a box of tea.

Snap lock bottom: 1-2-3

The snap lock bottom box (FEFCO 0215FEFCO code A four-digit code for a corrugated box style from the FEFCO catalogue, such as 0201 for the regular slotted carton. It names the shape, not the size. and its family) closes its bottom with four flaps that lock into each other, with no glue or tape. Fold the two side flaps in, then the flap with the notch over them, then the last flap, whose tongue goes into the notch: one, two, three. The carton still ships flat, and someone closes the bottom by hand before filling it. It usually holds more weight than a tuck end, and you choose its top: a tuck lid, a hang tab, flaps, a handle and more.

Crash lock bottom

The crash lock bottom box (also called auto-lock bottom, ECMA A60.20.00.03) has its bottom flaps glued once by the box maker, while the carton is still flat. Open the tube and the bottom swings into place and locks itself. Nobody folds flaps by hand, so it suits busy packing tables and heavier goods such as candles, mugs and bottles. The top closes with a tuck flap. The gluing is an extra step at the box maker, and our dieline does not mark where the glue goes, so agree that with them.

Which one to pick

• Light product: a tuck end is the simplest carton to make and to close.
• Heavier, packed by hand: a snap lock bottom, no glue at the bottom.
• Heavier, packed in quantity: a crash lock bottom that opens ready to fill.

Whichever you pick, the sizes you enter are measured inside, crease to crease. The tuck box sizes guide shows typical ones to start from.

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