Folding cartons — auto-lock (crash-lock) bottom
Custom Auto Lock Bottom Boxes
An auto lock bottom carton has a base that is glued during manufacture and locks itself into place the moment the flat carton is squared. There is nothing to fold at the bottom and nothing to push through. It is the carton for jars, bottles, candles and any product with weight, and the fastest tuck-top carton to pack by hand.
- Family
- Folding cartons
- Best for
- Jars, bottles, candles, heavier products
- Minimum order
- 50 boxes
- Sizing
- Made to your dimensions
Construction
How it is built, and how it opens.
How it is built
The blank is a tuck-end carton at the top and a four-panel base at the bottom. Two of the base panels carry glue tabs; on the folder-gluer the blank is folded twice and the base panels are glued to each other as the side seam is glued, so the flat carton leaves the line with a pre-formed bottom folded inside it. Those panels pull the base square as the walls are opened, which is why the style is also called crash-lock.
How it packs
The packer squeezes the flat carton open and the base drops and locks in one movement. The product is loaded from the top and the tuck flap closed, friction or slit lock. Because the base needs no folding, packing is faster than any other tuck carton and the base cannot be tucked wrongly. It also holds under load: the product's weight presses the base panels against each other, so a full jar sits on a floor, not on a flap.
Board and print
Heavier products call for heavier board, and auto-lock cartons commonly run at the upper end of the SBS range, up to 24 pt, or on kraft board from 18 pt to 24 pt. The board is printed directly, outside or inside and out, in CMYK or Pantone. Lamination is included; foil stamping, embossing, debossing, spot UV and a film-patched window are available. The glue area on the base is kept free of lamination so the bond holds.
Packing, shipping and cost
Auto-lock cartons ship flat, though the pre-glued base makes the flat blank a little thicker than a tuck-end carton, so a stack takes slightly more space. Per unit they cost more than a reverse tuck end because of the extra gluing, and a little more than a snap-lock bottom, which has no base glue. The return is packing speed and a base that carries weight; on a line packing jars all day the difference is paid back quickly.
What it suits
Where a auto lock bottom box earns its place.
Candles in glass
A carton whose base carries the jar's weight, often with a board insert to keep glass off the walls.
Bottles and jars
Skincare, food and beverage products where a tucked base would open under load.
Supplements
Bottles packed quickly on a line with clear compliance panels on the sides.
Small electronics
Chargers, speakers and accessories with weight, packed by hand with an insert.
Retail cubes
Square cartons for mugs, ornaments and gifts that stand on shelf without a rigid box.
Finished work
Folding cartons we have made.
Tuck-end carton · Print inside and out 
Tuck-top carton · Full-color print 
Straight tuck end carton · Full-color print 
Auto-lock bottom carton · Full-color print
- Internal dimensions (L × W × D) and, above all, the product's weight. Every carton is cut to your dimensions.
- Board: SBS or kraft, and gauge if you have a preference; heavier contents move up the range.
- Top closure: friction tuck or slit lock, and whether it should be reclosable.
- Print: outside only or inside and out, CMYK or Pantone, barcode and compliance panels; finishes: lamination, foil, embossing, spot UV, window.
- Insert, if the product is glass or should be held away from the walls.
Or consider
When another style does the job better.
Snap Lock Bottom
Choose it when the base can be folded by hand, no base glue is wanted and the flat blank should be as thin as possible.
Read the guideReverse Tuck End
Choose it for lighter products where a tucked base is enough and unit cost matters most.
Read the guideTwo Piece (Lid & Base)
Choose it when the product's price point calls for a wrapped rigid box rather than a printed carton.
Read the guide
Start a quote
Three answers is all it takes to open a job.
Structure, board and finishing come next — with our team, on the full quote form.
No account needed. Artwork and reference images can be attached on the next step.
Auto Lock Bottom questions
Before you ask.
Anything not covered here, put it in the notes on your quote and we will answer it directly.
Ask on your quoteWhat is an auto lock bottom box?
A folding carton whose base panels are glued during manufacture so the bottom locks into place as the flat carton is squared. Also called a crash-lock bottom.
Auto-lock or snap-lock bottom?
Auto-lock packs faster and needs no folding at the base, at a slightly higher unit cost. Snap-lock has no base glue and a thinner flat blank, but the packer folds and locks the base by hand.
How much weight can the base carry?
Considerably more than a tucked base, because the load sits on interlocked, glued panels. Send the product's weight and we set the board gauge to suit.
What is the minimum order for custom auto lock bottom boxes?
The minimum order for custom auto lock bottom boxes is 50 boxes, the same as every structure we make. Your quote shows the price at each quantity you ask for.
How long does production take?
Standard production is 10–12 working days from proof approval and payment. Ground shipping adds 3–5 working days, and delivery is free on every order.
Can I get a sample before the full run?
Standalone samples are chargeable, because making one box or a handful takes the same setup and production steps as a full run. On a qualifying bulk order, once the order is placed we produce a pre-production sample for your approval at no extra sample charge, and the remaining quantity runs after you approve it.
Same family
Other folding cartons styles.
Start here
Send us your dimensions. We’ll send back a box.
Or talk to a packaging specialist: (209) 444-0744