An auto bottom box, also called a crash lock or a 1-2-3 bottom, arrives flat with the base already glued into an interlocking pattern. Squeeze the box open and the bottom locks itself. No folding, no tabs to tuck, no second person holding it steady.
How the bottom locks
Four base panels are die cut so that they overlap in sequence, and two of them are glued to each other during manufacture. When the flat blank is squared up, that glued pair pulls the other two panels into place and they wedge against each other. The load then sits on all four panels rather than on a single tucked flap, which is why the base holds weight that a straight tuck would fail under.
Auto bottom against the alternatives
| Bottom style | Assembly | Load handling | Best fit |
|---|---|---|---|
| Auto bottom | One motion, pre-glued | Strongest of the folding carton bottoms | High volume counters, heavier or awkward contents |
| Straight tuck end | Fold and tuck each end by hand | Light contents only | Cosmetics, cartons that are filled by machine or slowly |
| Seal end | Glued or sealed shut after filling | Good, but the box is not reopenable cleanly | Sealed retail goods |
| Snap lock (1-2-3 by hand) | Three manual folds, no glue | Moderate | Low volume where assembly speed does not matter |
Where it pays for itself
The unit price of an auto bottom is a little higher than a plain tuck, because there is a gluing step. The saving is labour. If a member of staff assembles a hundred boxes during a lunch rush, the seconds per box are the real cost, and an auto bottom removes most of them. It also removes the failure mode where a rushed fold gives way and the contents land on the floor.
It is the wrong choice when the box is very small, because there is not enough panel to lock, and when the box will be machine erected on a line that expects a different base.
Specs to confirm before tooling
- Inside dimensions, given as length by width by depth, since the contents have to fit the finished interior.
- Board and caliper, matched to the weight the base has to carry.
- Whether the top is a tuck flap, a lid, or left open as a tray.
- Whether the box ships flat to you, which auto bottoms do, so plan the storage footprint for flat stock.
If you are still weighing this against a plain tuck design, the comparison sits on tuck end boxes, and the wider family of paperboard builds is covered at folding carton boxes.
Minimum, price and lead time
The minimum is 100 boxes. Bulk pricing starts at about $0.48 per unit and the figure for your job depends on size, board, print coverage and finish, so it is confirmed on your written quote. The die and plates, design support, free US shipping and a digital proof before printing are included in the order.
Turnaround is stated per product across three lanes. Rush is expedited production plus air freight and carries a premium of about 7 to 25% depending on the job. Standard moves by air. Cost saver moves by sea for the lowest freight cost and the longest wait. The floor is from about 7 business days plus 2 to 5 for delivery, and specialty imported items can run up to about 12 weeks. Production is at West Chicago in the United States or Guangzhou in China.
Send your inside dimensions, the weight the box has to carry and your quantity to /quote/, and ask for a dieline of the base so you can see the lock pattern before you approve it.
