Guide · updated 2 Nov 2026
Tuck end vs auto lock bottom
A tuck end box closes at the bottom with a tuck flap you push in by hand, while an auto lock bottom (also called crash lock) has four pre-glued bottom flaps that lock themselves when the flat carton is opened. Tuck ends suit light products and simple packing; auto bottoms pack faster and carry heavier products.
How does each bottom close?
Tuck end bottom: the bottom lid hinges on one panel, the two side dust flaps fold in first, and the lid's tuck flap slides inside, held by friction and slit locks. It is the bottom of a reverse tuck end or straight tuck end carton.
Auto lock bottom: four bottom flaps are folded and glued when the carton is made, so it still ships flat. When you square up the tube, the flaps swing down and lock into a flat floor in one motion. The top still closes with a tuck flap: a tuck top auto bottom carton.
Which carries more weight?
The auto lock bottom. Its flaps overlap into a locked floor, so the product's weight does not rest on a friction tuck. The rule of thumb on this site: a tuck end bottom on 18pt board for products up to about a pound; an auto lock or snap lock bottom above that, often on 20-24pt board; corrugated when the product is heavy or ships on its own.
Which is faster to pack?
The auto lock bottom: open the tube and the base is done. A tuck end bottom needs the dust flaps folded and the flap tucked, which takes a few extra seconds per carton. On a short run packed by hand that rarely matters; on thousands of cartons it adds up.
Which costs more?
On this site, a single printed piece at 3 x 3 x 7 in on 18pt SBS is listed at $5.59 as a reverse tuck end and $5.59 as a tuck top auto bottom. At volume, an auto bottom usually costs a little more than a tuck end because the blank is larger and the base is glued when the carton is made (industry rule of thumb). Auto bottom runs are quoted for your size; see all listed prices.
What about a snap lock bottom?
A snap lock bottom (often called 1-2-3 bottom) has four flaps that interlock by hand, with no glue on the base. It carries weight like an auto bottom but is slower to assemble, so it suits medium-weight products packed by hand.
| Tuck end bottom | Auto lock bottom | Snap lock bottom | |
|---|---|---|---|
| How it closes | Lid + tuck flap, by hand | Pre-glued flaps lock themselves | Four flaps interlock by hand |
| Glue on the base | No | Yes, when made | No |
| Packing speed | Slower | Fastest | Slowest |
| Weight (rule of thumb) | Up to about 1 lb | About 1 lb and up | About 1 lb and up |
| Dieline | RTE generator | Auto bottom generator | Snap lock generator |
Questions
Is a crash lock bottom the same as an auto lock bottom?
Yes. Crash lock, auto lock and auto bottom are names for the same base: four bottom flaps glued at the factory so they fold flat and spring into a locked floor when the carton is opened. The top usually closes with a tuck flap.
Is a snap lock bottom the same as an auto bottom?
No. A snap lock bottom (often called 1-2-3 bottom) has four flaps that you interlock by hand, with no glue. It is strong like an auto bottom but slower to assemble, and it needs no gluing of the base when the carton is made.
Which bottom should I choose for a heavy product?
Above about a pound, an auto lock bottom or a snap lock bottom is the usual choice, often on 20-24pt board, because the base does not rely on a friction tuck holding the weight. That is a rule of thumb; heavier still, or shipped alone, moves to corrugated.
Can I make a dieline for both?
Yes. The dieline generator draws reverse and straight tuck end, tuck top auto bottom and tuck top snap lock bottom cartons at any inside size, with bleed and safe lines, and downloads SVG, PDF or DXF.