A dieline is the flat map of a package before it is cut and folded. If a printer has ever sent you one and it felt like you were looking at an engineering drawing, this guide is for you.
By the end you will know what every line means, where artwork can and cannot go, how to work out which way each panel faces, and why a pretty mockup is not the same thing as a file a printer can use.
What a dieline actually is
The name comes from the steel-rule die, the sharp-edged tool a converter uses to cut and crease a flat sheet of board. The dieline is the drawing that die is made from. Everything about the finished pack (its size, its flaps, where it folds, where glue goes) is encoded in that flat drawing.
Because the die is physical, the dieline is exact. A millimetre off on a fold line becomes a lid that does not close or a flap that bows open. That is why printers ask for artwork placed on their dieline rather than a loose image or a mockup.
Not every format uses a cutting die in the same way. Cups, cans and labels are printed flat and then formed or wrapped, and pouches are printed on film and heat-sealed. They still have a flat template with the same kinds of lines, so everything below applies to them too.
The four lines you need to know
Colours and line styles vary between suppliers, so always check the legend on the dieline you are given. These are the most common conventions.
- Cut line. Usually solid, often red or black. This is the outside edge of the pack and the edges of any windows or holes. Anything outside it is waste.
- Fold or crease line. Usually dashed, often blue or green. The board is scored here and bends. Text that crosses a fold cracks and is hard to read, so keep type at least 3 mm clear of it.
- Bleed line. A line outside the cut line, typically 3 mm away. You extend backgrounds and images to the bleed so that if the cut shifts slightly (it always does, by a fraction of a millimetre) no white edge appears.
- Safe area. A line inside the cut, typically 3 mm to 5 mm in. Keep text, logos and barcodes inside it. Anything between the safe area and the cut line risks being trimmed or wrapping around an edge.
For a deeper look at the two margins, read bleed vs safe area in packaging.
Other marks you may see
Supplier dielines often carry extra information. None of it prints, but all of it matters.
- Glue area. Usually hatched or shaded. Nothing should print here, because ink and coatings can stop the glue holding.
- Perforation line. Often dash-dot. Used for tear strips and easy-open panels.
- Dimensions. Measurements written along the edges, usually in millimetres. Check whether they are internal or external before you trust them.
- Panel labels. Words like Front, Back, Lid or Base written on each panel. Very helpful when the layout is confusing.
- Notes and title block. The format name, board grade, size and sometimes a job number. Keep this information with your files so everyone is talking about the same dieline.
Reading the layout
Panels on a dieline are laid out as they unfold, which means some are upside down or sideways relative to how they appear on the finished pack. On a mailer box the front tuck flap often sits upside down at the top of the sheet. On a cup the whole design sits on a curve, so a straight line of text drawn flat ends up level only if it follows that curve.
The trick is to pick one panel as your front, then trace how each neighbouring panel attaches to it along a fold line. Ask yourself: when this panel folds up, is its top edge the edge touching the fold, or the far edge? If you cannot picture it, that is what a 3D preview is for. In Packaroo you see your artwork on the pack in a live 3D preview as you design, so you can check which way every panel faces before anything is printed.
Worked example: a mailer box dieline
A roll-end tuck front mailer is one of the most common formats for small brands, and its dieline confuses almost everyone the first time. Here is how to read it step by step.
- Find the base. It is the large rectangle near the middle with fold lines on all four sides. This is the floor of the box.
- Find the lid. It is the other large rectangle, joined to the base along the back wall. It usually carries your main artwork.
- Find the front tuck. The narrow panel on the far edge of the lid tucks into the front of the box. Artwork here is seen upside down on the flat sheet but reads correctly when the box is closed.
- Find the side walls. These are the panels that roll over and lock in. On many mailers they are double-thickness, so part of each wall is hidden inside.
- Mark the inside. If you are printing inside the lid for an unboxing message, remember the inside print is a separate side of the sheet with its own orientation.
Once you have labelled each panel this way, placing artwork is much less stressful. You can try this on the mailer box dieline.
Common mistakes
- Designing to the cut line instead of the bleed, which leaves white slivers on edges.
- Putting a logo across a fold, where it cracks and distorts.
- Ignoring the glue flap and printing artwork that ends up hidden or stops the glue holding.
- Using a dieline from a different supplier. Fold allowances change with board thickness, so a dieline drawn for E-flute (about 1.5 mm) does not fit a B-flute box (about 3 mm).
- Sending a JPEG of the dieline with artwork pasted on top instead of a vector PDF with the dieline on its own layer.
- Leaving the dieline set to print, so the cut and crease lines appear on the finished pack.
Where to get a correct dieline
Your supplier will send one for their exact board once you have agreed a format and size. That dieline is the final word, because only the supplier knows the board and tooling they will use.
If you are earlier than that and want to design first, open the format in Packaroo and set your inside dimensions. Every Packaroo dieline marks cut, fold, bleed and safe area. When you are ready, export the spec pack so the supplier knows exactly which dieline and dimensions you used and can adjust for their board. Expect small changes at this stage: a supplier may adjust fold allowances or flap sizes to suit their board, and that is normal. The spec pack includes the dieline at 1:1 scale with cut and crease lines, so prepress can compare it with their own.
A quick checklist before you place artwork
- You know which line style means cut, fold, bleed and safe area on this particular dieline.
- Every panel is labelled or you have traced its orientation from the front panel.
- The dieline matches the board your supplier will use, or the supplier has confirmed it.
- Dimensions are confirmed as internal or external.
- Glue areas and hidden panels are marked so you do not waste artwork on them.
- The dieline sits on its own layer that is set not to print.
If you can tick all six, you are ready to design. Confirm anything you are unsure of with your supplier before you start, not after.
Next step
Open a format in Packaroo, drop in a logo and watch it appear on the pack in 3D. It is the fastest way to learn how a dieline works, and you can start on the free plan. You only pay when you export a spec pack, A$15 one-time.
Related guides: Bleed vs safe area and What is a packaging spec sheet.