01What a folding carton is (and is not)
PRINTING United Alliance describes folding cartons as boxes made from a single sheet of board that feels like thick cardstock, printed, laminated, die cut, folded and glued, then typically shipped flat to a packager who folds them into shape. Shipping flat is the point: the association notes it saves on shipping, against a box that travels assembled.
A rigid box is thick greyboard wrapped in paper and glued into its final shape, so it never folds flat. A corrugated box has a fluted layer between two liners, which is what lets it take a beating in a parcel network. A folding carton is one solid layer of board, made to sell on a shelf, not to protect in a truck.
02Paperboard grades: SBS, CUK and CRB
North America has three main consumer boxboard grades; the names tell you the fiber. The AICC, the independent box makers’ association, says SBS and CUK generally contain at least 80% virgin wood pulp and are used where print quality and strength matter.
| Grade | What it is | Typical uses |
|---|---|---|
| SBS (solid bleached sulfate) | Premium white board from bleached chemical pulp | High-end printed cartons; cup stock, ice cream cartons and liquid packaging |
| CUK or SUS (coated unbleached kraft) | Strong kraft board with a white coated surface on one side and a brown kraft back; CUK and SUS are the same product under two names | Beverage carriers and frozen food, where wet and tear strength matter |
| CRB (coated recycled board) | Economical board made from recycled fiber; also called white-lined chip | Cereal boxes, powdered laundry detergent |
You will also hear FBB (folding boxboard), a multi-layer grade the AICC calls popular in Europe. Ask the supplier which board, mill and caliper it proposes, and get a board sample. For a brown look, CUK board and board faced with kraft paper print differently; see a printed sample.
03Caliper: points vs GSM
Caliper is board thickness, quoted in the US in points: one point is a thousandth of an inch, so 18 point board is 0.018 inch (about 0.46 mm). Some suppliers quote board by weight in GSM instead, and the two do not convert cleanly: a bulky uncoated board can be thicker than a heavier coated one. Get both numbers for the exact board and compare samples, not spec sheets.
PRINTING United Alliance puts most folding cartons at 14 to 24 point single-ply board, often chosen by the carton size and the weight of what goes inside.
04Types of folding cartons: the common styles
Tuck and lock styles are a four-panel tube glued at the side seam; what changes is how the ends close.
- Straight tuck end: the top and bottom closures both tuck in from the same side of the carton.
- Reverse tuck end: the top tucks one way and the bottom the other.
- Auto lock bottom (crash lock bottom): pre-glued bottom flaps snap into place when the flat carton is opened; the top tucks.
- 1-2-3 bottom (snap lock): the bottom flaps interlock when folded in order, with no glue.
- Seal end: the end flaps are glued shut at packing instead of tucked.
- Sleeve: an open-ended tube that slides over a tray or product, a simple way to add print to a plain box.
- Trays, display boxes and pillow boxes: other shapes from the same die-cut board.
The style lives in the dieline, the flat template the printer cuts. Our box styles entry covers the names you will see on quotes.
05How folding cartons are made
- Printing: sheets of board are printed with several cartons per sheet, laid out to waste as little board as possible. Offset suits high-volume runs, flexo long static runs, digital short runs and versions. See printing methods.
- Coating and laminating: a varnish or UV coating over the colors, or a laminated foil, metallized film or paper.
- Die cutting and creasing: a form set with knives and creasing rules cuts each carton out and presses the fold lines (scores). Embossing can be added at this stage.
- Folding and gluing: high-speed machines fold and glue each carton along its creases, then the flat cartons are packed for shipment.
That is the sequence Pro Carton, the European carton makers’ association, describes. Plates and cutting forms are made per design, so the unit price usually falls as quantity rises. Ask each supplier for its minimum and the price at two quantities; our guide to MOQ covers how to read those quotes.
06Finishes
Folding cartons take most of the same finishes as rigid boxes, printed straight onto the board: foil stamping, matte, gloss or soft-touch lamination and coatings, spot UV, and embossing and debossing. Window patches (a die-cut hole with clear film) show the product. Each adds a step and cost, and foil, windows and plastic films can affect a recyclable claim.
07Folding carton vs rigid box vs corrugated mailer
| Folding carton | Rigid box | Corrugated mailer | |
|---|---|---|---|
| Material | One layer of paperboard | Thick greyboard wrapped in paper | Fluted board between two liners |
| Ships to you | Flat | Assembled (unless collapsible) | Flat |
| Job | Retail shelf and branding | Premium presentation, kept by the customer | Survives parcel shipping and unboxing |
| Survives a parcel network alone | No | Usually needs a shipper | Yes, if specced for the weight |
| Unit cost | Lower than a rigid box | Highest | Depends on size and print |
Online brands often put a folding carton inside a mailer box or shipper. If you never sell on a shelf, a printed mailer alone may do both jobs.
08Recyclable claims, FSC and food contact
Under the FTC Green Guides (16 CFR 260.12), an unqualified "recyclable" claim needs recycling facilities available to at least 60% of the consumers or communities where the item is sold; below that, qualify it. If any component significantly limits recycling, a recyclable claim is deceptive. The Paperboard Packaging Council says that since 2011, paperboard packaging has been collected for recycling in over 60% of US communities. Its free recyclable logo is not for boxes with direct wet food contact or UV-printed boxes, and it warns that not all municipalities can recycle cartons with foil or windows.
Recycled content claims (16 CFR 260.13) are unqualified only if the whole package, minor parts aside, is recycled material. A carton that is partly recycled states the amount or percentage by weight. Get the recycled share of the board in writing before you print a number.
For the FSC label, the printer needs its own FSC chain-of-custody certificate, which is what lets an organization put the FSC label on finished products, according to FSC. A brand that only sells the product generally uses FSC’s promotional license instead.
If the board touches food, FDA rules list substances that may be used in the food-contact surface of paper and paperboard: 21 CFR 176.170 for aqueous and fatty foods, 21 CFR 176.180 for dry food. Ask the supplier for a written statement that the board, coatings and inks on the food-contact side comply for your food type.
09How to spec it with a supplier
Carton prices swing with board grade, caliper and finishes, so name all three. Put the structure, board and finishes in your packaging spec or tech pack, with a dieline. The Vault lists packaging factories with contacts; the public list is at packaging manufacturers.
| No. | Field | What to write |
|---|---|---|
| 01 | Style | Reverse tuck, straight tuck, auto lock bottom, 1-2-3 bottom, seal end or sleeve; with dieline |
| 02 | Dimensions | Internal L x W x D in mm (length and width of the opening first), with tolerance |
| 03 | Board | Grade (SBS, CUK, CRB), caliper in points or GSM, mill or brand if it matters, FSC or recycled content if you will claim it |
| 04 | CMYK and Pantone references, number of colors, inside print if any; see Pantone vs CMYK | |
| 05 | Finishes | Coating or lamination type, foil color and area, spot UV, emboss or deboss, window size and film |
| 06 | Proof | Digital proof plus a printed or structural sample before bulk; see proofs |
| 07 | Packing | Cartons per bundle and per master carton, master carton size and weight, shipped flat |
Questions to ask the supplier
- Which board grade, caliper and mill do you recommend for this product weight?
- What is your minimum per design, and the unit price at my quantity and at double it?
- Can you send your FSC chain-of-custody certificate and code if I am paying for FSC board?
- For food products: can you confirm in writing that the board, coating and inks comply with FDA rules for my food type?
10FAQ
Q01What is a folding carton?
A box made from one sheet of paperboard that is printed, die cut, scored, folded and glued, then shipped flat and folded into shape when the product is packed.
Q02What are the types of folding cartons?
The common styles are straight tuck end, reverse tuck end, auto lock (crash lock) bottom, 1-2-3 bottom, seal end, sleeves and trays. They differ mainly in how the ends close. Ask the supplier which closure suits your product’s weight.
Q03What is an auto lock bottom box?
A carton whose bottom flaps are pre-glued at the factory, so the bottom locks into place when you open the flat carton. It is the same as a crash lock bottom box.
Q04Are folding cartons recyclable?
The Paperboard Packaging Council says paperboard packaging is collected for recycling in over 60% of US communities. Not all communities can recycle cartons with foil or windows, and PPC’s recyclable logo is not for cartons with direct wet food contact or UV printing, which matters before you print "recyclable" under the FTC Green Guides.