Set up a brochure at trim size plus 3mm bleed on every outer edge, keep text 5mm inside the trim and 6mm clear of any fold, put fold marks on a layer that does not print, and make the panel that tucks inside about 2mm narrower than the other two. Export as CMYK PDF with crop marks and bleed included. That is the whole spec.
Everything below is the reasoning, the numbers for A4, and the handful of things that cause reprints.
Bleed: 3mm, and what it is actually for
Bleed is extra artwork that extends past the line where the paper gets cut. It exists because guillotines are not perfect. A stack of 500 sheets shifts by a fraction of a millimetre as the blade comes down, so the cut lands slightly off. If your background colour stops exactly at the trim line, some of those sheets come back with a thin white sliver along one edge.
Three millimetres on every outer edge is the standard. Push your background, images and colour blocks out to the bleed line, then forget about them — the bleed area is designed to be thrown away.
Two things people get wrong:
Bleed goes on the outside edges only, not on the folds. A fold is not a cut.
Bleed is not a margin. Nothing you want to keep goes in the bleed area. It is sacrificial.
If nothing in your design touches an edge — a white brochure with a centred logo — you technically do not need bleed. Set it anyway. It costs nothing and it means the file is never the reason a job is held.
Safe area: 5mm from trim, 6mm from folds
The same cutting tolerance that eats your background can also eat your text. Keep everything you need to be readable at least 5mm inside the trim line.
At folds, give yourself more. Folding machines have their own tolerance, usually a millimetre or two, and a crease through a word is permanent in a way a slightly-off cut is not. 6mm either side of each crease is a sensible working minimum, more on heavy card.
Three rules that follow:
No text crosses a fold.
No logo crosses a fold.
No face crosses a fold. An image can run across a crease; it should not run through somebody's eye.
Backgrounds, textures and colour fields can cross freely. That is what folds are for.
The panel that has to be narrower
This is the spec that no preset sets for you and that costs the most when it is missed.
On a roll fold — the standard trifold, where the panels roll in on each other like a letter going into an envelope — one panel ends up inside the other two when the piece is closed. If all three panels are the same width, that inner panel runs into the crease as it closes. The brochure bulges, will not lie flat, and will not stack.
On thin paper you can get away with it. On the 250 to 300 gsm card an actual brochure is printed on, you cannot.
The allowance is about 2mm, with a trade range of roughly 1.5mm to 3mm. Heavier stock, bigger allowance.
For an A4 landscape trifold, 297mm wide:
Two outer panels at 100mm
Tuck-in panel at 97mm
100 + 100 + 97 = 297mm
Equal thirds would be 99mm each. On screen the difference is invisible. In the hand it is the difference between a brochure that closes and one that does not.
Two details. The narrower panel sits on the same side of the sheet on both faces, so your fold guides have to line up front and back. And a Z-fold is different — the panels zigzag, nothing nests inside anything, so all three panels are equal at 99mm with no allowance at all. Converting a roll fold layout to a Z-fold is not a matter of rearranging; the widths change.
Which panel is the tuck-in, and therefore where your cover goes, is a separate question and the one people get wrong most often. It is worked through in trifold brochure panels.
Fold marks are not crop marks
Crop marks tell the printer where to cut. Fold marks tell them where to crease. They are different marks and most export presets only give you the first.
Put fold marks on their own layer, set not to print, with short dashed lines sitting outside the trim area so they end up in the bleed and get cut off. Never draw a fold line across the artwork itself, because sooner or later it prints.
Then label the file. a4-trifold-roll-fold-cover-right.pdf takes ten seconds to type and removes an entire category of problem, which is the printer folding it the way they usually fold things.
Colour: CMYK, and the black problem
Print is CMYK. Your screen is RGB. Anything bright and saturated — particularly vivid blues, oranges and greens — will come back duller than it looked. Convert to CMYK while you are designing, not at export, so you are making decisions against what you will actually get.
The specific trap is black.
Body text: 100% K only. Nothing else. Black text built from all four plates will show colour fringing wherever the plates are a hair out of register, and small type is where that shows worst.
Large black areas: 100% K on its own looks washed out and grey across a big field. Use a rich black — a common recipe is C60 M40 Y40 K100 — but confirm it with your printer, because total ink limits vary and some presses will reject anything over about 300%.
If you have a brand colour that has to be exact across a print run, that is a Pantone spot colour conversation and it costs extra. Worth it for a logo on a cover; not worth it for a body-text accent.
Images: 300 dpi at final size
The phrase that matters is at final size. A 300 dpi image is only 300 dpi at the dimensions it is placed at. Scale a 300 dpi photo up to twice the size and you have a 150 dpi photo, which will look soft on card.
Quick arithmetic: an A4 page at 300 dpi needs an image around 2480 by 3508 pixels. A full-bleed A4 image needs a bit more to cover the bleed.
Also: do not pull images off a website. Web images are 72 to 150 dpi and usually RGB and usually already compressed. They look acceptable on a laptop and visibly rough on 300 gsm card.
Fonts: outline or embed
Either embed the fonts in the PDF — which standard print export presets do automatically — or convert type to outlines before exporting. Embedding is better because the text stays searchable and editable if something has to change. Outlining is the safe fallback when a font has a licence that blocks embedding.
What you must not do is send a PDF with unembedded fonts. The printer's machine substitutes something, your layout reflows, and nobody notices until it is printed.
What the printer actually wants
Most problems are not design problems, they are handover problems. A clean submission is:
One PDF, not a folder of JPEGs and not a Canva share link.
Pages in reading order, one spread per page, with outside and inside clearly identified.
Bleed included and crop marks on. In most export dialogs this is "Use Document Bleed Settings" plus "Crop Marks" — both off by default.
PDF/X-1a or PDF/X-4 if the printer names a standard. If they do not, a press-quality PDF with bleed is fine.
CMYK, with any spot colours named rather than left as unconverted RGB.
A filename that says what it is, including the fold.
And ask for a proof. A digital proof is usually free and catches page order and missing bleed. A physical proof costs money and catches colour and stock. On a run of 500 on card, a physical proof is cheap insurance; on a run of 25, a digital one is enough.
The checklist
Trim size set, plus 3mm bleed on all outer edges
Background and images pushed out to the bleed line
Text and logos 5mm inside trim, 6mm clear of folds
Roll fold: tuck-in panel 2mm narrower, matched front and back
Z-fold: three equal panels, no allowance
Fold marks on a non-printing layer, outside the trim
Document in CMYK; body text 100% K only
Rich black for large black areas, within the printer's ink limit
Every image 300 dpi at placed size
Fonts embedded or outlined
Single PDF, pages in order, crop marks and bleed on
Filename states size, fold and which side is the cover
Proof requested
One last check that is not in any spec sheet
Every item above is verifiable from the file. The thing you cannot check from a file is whether the brochure works as an object — whether the cover reads from arm's length, whether the type is comfortable at finished size, whether something important is sitting where a crease will land.
Put the artwork on a brochure mockup and look at it folded before you send anything. It takes two minutes. Printing a sample costs money and three days; this costs neither, and it catches the errors that are expensive precisely because you only find them when the box arrives.
Still deciding whether you need a brochure at all, or a flyer or a booklet? The formats and what they cost are set out in brochure vs flyer vs booklet.