A snap lock bottom is a carton base made from four flaps that fold in a set order and lock against one another. The name 1-2-3 bottom comes from that sequence: three folds and a final flap that snaps under the others to hold everything closed. No glue, no tape, no tooling beyond the die.
How it works
Two of the four flaps are cut with a tab and a slot arrangement. The packer folds the first flap in, then the second, then the third, then pushes the fourth flap past the others so its tab seats under them. The load in the carton pushes down on the locked flaps, which pushes them tighter against each other. That is why the base gets stronger under load rather than weaker, and it is the main reason to choose it over a plain tuck bottom.
Compared to the alternatives
| Bottom style | Assembly | Load capacity | Suits |
|---|---|---|---|
| Snap lock (1-2-3) | Hand folded, no glue | Good for medium weight | Retail cartons packed by hand, candles, jars, bottles |
| Auto bottom (crash lock) | Pre glued, pops open | Good for medium to heavy | Higher volume packing lines where speed matters |
| Tuck end | Flap tucks into a slot | Light | Light products, cosmetics, small cartons |
| Seal end | Glued closed after filling | Good, tamper evident | Automated filling, food and pharmaceutical cartons |
When to specify it
Choose a snap lock bottom when the product has real weight for its size, when the cartons are assembled by hand, and when you want them to ship and store flat. Candle jars, glass bottles, jars of preserves and heavier cosmetics are common cases. Choose an auto bottom instead when someone is assembling hundreds an hour and the seconds per carton matter, since the glued base opens in one motion. Choose a tuck end when the product is light and the carton is small enough that the base is not carrying much at all.
What to check on the dieline
- Flap lengths relative to the carton width, since the flaps have to overlap enough to lock.
- The caliper of the board: a board too heavy for the size fights the fold, one too light lets the lock pull free.
- Whether the bottom will be visible in use, because the interlocking flaps are more visible than a glued base.
- Crease quality, which is what makes the fold sequence easy or maddening for whoever is assembling.
Board and print
Snap lock bottoms are usually run in folding carton board, and the caliper choice is a balance between the lock holding and the carton folding easily. If your product is heavy enough that you are worried, quote both a heavier caliper and an auto bottom and compare. Our guides on auto bottom boxes and tuck end boxes cover the alternatives, and for the interlocking display format see 1-2-3 bottom display lid boxes.
Ordering and turnaround
Minimum order is 100 cartons, from about $0.48 per unit at bulk volumes, confirmed on your written quote. The die, the plates, design support, US shipping and a digital proof before anything prints are included. We produce in West Chicago in the US and in Guangzhou in China. Turnaround is quoted per product in three lanes: rush (expedited production plus air freight), standard (air) and cost saver (sea), from about 7 business days in production plus 2 to 5 days for delivery.
Tell us the product weight and how the cartons will be assembled, and we will recommend a bottom style with the dieline. Request a quote to start.
