The Fold · From the factory floor
What is a dieline?
A complete reference to the dieline — every line on it, what bleed and safe area really mean, and why the picture your design tool gave you isn’t one.
The short answer
A dieline is the flat, full-scale blueprint a package is cut, creased and folded from. It shows the package unfolded, with every knife line, fold, glue flap, bleed edge and safe area drawn as a separate line. It is a manufacturing drawing, not a picture of the finished package — and it is the one file a printer cannot start without.
If you have landed here, someone has probably just asked you for a dieline and you weren’t expecting the question. That is normal. It is the point where designing a package stops being design and starts being manufacturing, and almost nothing you have made up to that moment carries across.
I run a packaging factory. We receive files all day, and the single most common reason a project stalls in week one is that the brand has a beautiful image of their package and no dieline underneath it. So here is the whole thing written out properly — what a dieline is, what each line on it does, the two numbers everybody gets wrong, and how to tell in about five seconds whether what you are holding is a real one.
Why it’s called a dieline
A die is a physical tool. For most paperboard packaging it is a thick plywood board with strips of steel rule bent and hammered into slots in it — sharp-edged rule where the board must be cut, blunt rounded rule where it must be creased. That die is pressed into a sheet of board under tonnes of pressure and the flat package pops out in one hit.
The dieline is the drawing that tool is built from. Every line you put on it becomes a piece of steel. That is the mental model worth keeping: you are not drawing a picture of a box, you are giving a toolmaker a set of instructions in a language where a red line and a blue line mean two physically different pieces of metal.
Flexible packaging — pouches, bags, films — has no steel die in the same sense, but the file works the same way. The knife becomes a rotary blade or a laser, and the folds become heat seals. The drawing is still called a dieline, and it still carries the same layers.
The lines on a dieline, and what each one does
A dieline that only has an outline is not finished. A production file separates the geometry by purpose, because different machines read different lines. These are the seven layers on every file TWOFORM produces, in the exact colours the factory sees them in:
Every production file TWOFORM exports carries this key printed on the sheet itself, so whoever opens it downstream never has to guess which colour is the knife.
The parts of the blank
Unfold any package and it resolves into a small number of named parts. Printers use these words on the phone, so they are worth having.
Panels
The faces you actually see when it is assembled — front, back, sides, top, bottom. On a carton they sit in a row separated by creases, so the flat blank reads left to right in the order the box wraps around itself. This is why artwork laid out on a dieline looks scrambled: the back panel is often upside down relative to the front, because when it folds over, it rights itself.
The glue tab
A narrow flap on one end of the panel row that gets adhesive and bonds to the opposite panel, closing the box into a tube. On corrugated it is a real, fixed piece of engineering — our corrugated constructions use a 35 mm joint, which sits in the middle of the 32–40 mm range the trade works to. Print across it at your peril: ink and varnish can stop the glue keying to the board, and the box opens itself in a warehouse three weeks later.
Dust flaps and tuck flaps
The smaller flaps at the top and bottom. Dust flaps fold in first and close the corners; the tuck flap folds down over them and slots in. On a tuck-end carton these are the entire closing mechanism, and their proportions are not free — they are derived from the box’s own depth, which is why a carton that is too shallow for its footprint simply cannot be built.
Fabrication features
Anything made rather than cut: a heat seal on a pouch, a zipper track, a tear notch, a hang hole, a window cut-out. These live on their own layer because a different machine makes each one.
Bleed and safe area — the two numbers everyone gets wrong
Almost every rejected file we see fails on one of these two, so it is worth being blunt about them.
Artwork has to run past the cut line by 3 mm on every edge. Presses and dies both drift a fraction of a millimetre; without bleed that drift shows up as a hairline of bare white board along an edge, on some of the run and not others. Every construction we produce declares 3 mm — boards, film, corrugated, labels, all of it. One number, no exceptions to remember.
The mirror image. Every logo, barcode, ingredient panel and legal line stays at least 3 mm inside the cut and inside any fold. The same drift that eats an unbled edge will shave a barcode, and a barcode bent through a crease will not scan at all. We inset 2 mm rather than 3 mm on cylindrical items like koozies, where the seam weld takes the margin instead.
The simplest way to hold it: bleed is for backgrounds, safe area is for anything that has to be readable. The two ranges never overlap, and the gap between them is the tolerance the whole process runs on.
A mockup is not a dieline. Neither is a template.
This is the section that saves people the most time, because the three things get used interchangeably and they are not remotely the same object.
This matters more than it used to, because of how most AI packaging tools are built. The common approach is a compositor: the AI generates a flat image, and the software wraps that image onto a 3D shape to show you a package. What comes out is a mockup. It looks finished, and there is no dieline under it, because the artwork was never generated on one in the first place — it was generated as a picture and mapped afterwards.
That is the difference between seeing your package and being able to order it. It is also why so many people arrive at a printer holding an image they love and get told to start again. I’ve written about that specific failure at length — the melted text, the invented barcodes, the logo that changes slightly on every panel.
Why your dimensions might not be buildable
A dieline is not just a shape, it is a shape that has to survive a machine. Two boxes with identical volume can behave completely differently on a folder-gluer, and a drawing tool that lets you type any number will happily hand you something that cannot be made.
These are the working envelopes our engine holds each family to — the real floors and ceilings, not marketing ranges:
And the per-axis range is only the first gate. A folding carton also has to clear three proportion rules that have nothing to do with how big it is:
- It has to fit the press sheet. The flat blank — panels plus glue tab plus flaps — must fit inside a 28 inch sheet. A box can be well within the size limits on every axis and still fail here, because the blank is far wider than the finished box.
- It can’t be too slender. Height is capped at five times the square root of length × width. Past that a tall narrow carton buckles under its own contents.
- It can’t be too flat. Height has to be at least the widest dimension divided by five, or the tray sags and the flaps have nothing to grip.
Downloading a free template skips all of this. The template is a drawing; it does not know what you are putting in it and nothing checks the result. That is fine when your product happens to match the template exactly, and a wasted month when it doesn’t.
What your printer actually needs from you
If you take one practical thing from this page, take this list. It is what we ask for, and it is close to universal:
- Vector, not raster. PDF, AI, SVG or EPS. A JPG of a dieline is not a dieline — there is no path for a knife to follow.
- Lines separated. Cut, crease, bleed, safe and glue on their own named layers or spot colours, so the die-cutter can isolate the knife without guessing.
- Art at 100% scale. Built on the dieline at true size, not scaled to fit afterwards.
- 3 mm bleed on every edge, with critical copy 3 mm inside the safe line.
- Fonts outlined, images embedded. Live type reflows on a machine that doesn’t have your font.
- Your real barcode. Generated from your real GTIN, placed on a quiet background with its margins intact — never drawn, never generated as artwork.
- Colours specified. CMYK, or named spot inks if you need an exact brand colour to hold across runs.
Number six is the one that costs people money. A barcode is data, not decoration. If it was produced as part of an image it will not scan, and you will find out at a retailer’s dock rather than at the proof stage.
Where TWOFORM fits
We built TWOFORM because of this exact gap. Rather than generating a picture and mapping it onto a shape afterwards, it draws the real dieline first — to your dimensions, with the cut, crease, glue, bleed and safe lines all present — and the AI designs onto that. What you look at on screen is the construction, so the thing you download is the thing the factory cuts.
Because the dielines are drawn to your dimensions rather than pulled from a library, there are over 500,000 buildable ones across the constructions we make, and every one is checked against the limits above as it is drawn. If a size cannot be built, it tells you before you have designed anything on it.
Generate a real dieline, free
Pick a construction, type your dimensions, and watch the flat blank draw itself with every line in place. No account needed to see it.
Open the dieline generator →Common questions
What is a dieline?
A dieline is the flat, full-scale blueprint a package is cut, creased and folded from. It shows the unfolded shape of the package with every knife line, every fold, the glue flaps, the bleed and the safe area marked as separate lines. It is the file a printer needs before they can make anything, and it is a manufacturing drawing rather than a picture of the finished package.
What is the difference between a dieline and a mockup?
A dieline is the flat production file the die is built from; a mockup is a rendered image of the finished package used to show people what it will look like. A mockup has no knife lines, no creases, no glue flaps, no bleed and no scale, so it cannot be manufactured from. Most AI packaging tools output a mockup — a flat image wrapped onto a 3D shape — which is why printers ask for the dieline instead.
How much bleed does a dieline need?
3 mm of bleed on every cut edge is the working standard, and it is what TWOFORM puts on every construction it produces — cartons, corrugated, rigid boxes, pouches, mailers and labels alike. Bleed is artwork that runs past the knife so that normal cutting drift still lands on printed stock instead of exposing a white edge.
What is the safe area on a dieline?
The safe area is an inset from every cut and fold that all critical artwork — logos, barcodes, nutrition panels, legal copy — must stay inside. TWOFORM insets 3 mm on printable panels, and 2 mm on cylindrical items such as koozies where the seam weld eats the margin. Anything outside the safe area risks being trimmed off or bent through a fold.
Can I just download a free dieline template?
You can, but a template is a fixed size. It only works if your product happens to match that exact size, and it is a drawing rather than a validated construction, so nothing checks that the proportions can actually be folded, glued and shipped. A generated dieline is built to your dimensions and validated against real manufacturing limits as it is drawn.
What file format should a dieline be?
Vector — PDF, AI, SVG or EPS — with the cut, crease, bleed and safe lines on separate named layers or spot colours so the die-cutter can isolate the knife. A JPG or PNG of a dieline is not usable: raster has no path for a knife to follow.