Three things about brochures that are not obvious and each of which ruins a print run: unequal panels, effective resolution, and what borderless actually means.
The panels are not equal
This is the single most common brochure mistake and it is invisible on screen. A tri-fold divided into three equal thirds will not fold flat.
The panel that folds inwards has to fit inside the other two once folded. If it is the same width it meets the fold and buckles, producing a brochure that springs open and creases along the inner panel.
| Panel (A4 landscape, 297mm) | Width |
|---|---|
| Left, folds in | 96mm |
| Middle | 99mm |
| Right, outermost | 102mm |
The exact figures depend on paper thickness — heavier stock needs more allowance — but the principle holds for any roll fold. Ask the printer for their template if there is one; most supply them, and it removes the question entirely.
Panel order is not reading order
On the flat sheet the panels are not laid out in the order a reader encounters them, and getting this wrong is the other classic brochure failure.
For a tri-fold, the front cover is the rightmost panel of the outside sheet, the back cover is the middle panel, and the panel that folds in first is on the left. The inside sheet reads left to right as a spread.
Fold a sheet of paper, number the panels as you would encounter them, then unfold it and see where the numbers landed. Two minutes with a real sheet prevents the error that a screen layout makes almost inevitable.
Design decisions that matter
- Bleed 3mm on every edge, plus a 5mm safe margin inside the trim. Nothing important goes near a fold.
- Keep text off the folds. A heading crossing a crease is unreadable and the crease will not land exactly where you think.
- One idea per panel. The reader encounters them one at a time, not as a spread.
- The front panel does one job: making someone open it. Not summarising the contents.
- CMYK, not RGB, and check contrast — a colour combination that reads well on a backlit screen can be muddy on paper.
The fold rule is worth being strict about. Folding is mechanical and has a tolerance of a millimetre or two, so anything placed exactly on a fold line will be slightly off on some copies and badly off on a few.
A PDF does not have a DPI
This confuses people because printers ask for one. The document itself has no resolution — it is a page described in points, and vector content is resolution-independent by nature.
What has a resolution is each individual image inside it, and the number that matters is the effective DPI: the image's pixel dimensions divided by the physical size it has been placed at.
A 1200-pixel-wide photograph placed 4 inches wide is 300 DPI and fine. The same image stretched to 8 inches is 150 DPI and will look soft in print. Scaling an image up in the layout lowers its effective resolution, which is why a picture that looked crisp in the design comes back disappointing.
Checking it
- Acrobat Pro: Print Production → Preflight has a resolution check, and Output Preview → Object Inspector reports the effective DPI of whatever you click.
- Command line:
pdfimages -listfrom the Poppler tools prints every image with its dimensions and effective resolution. - Rough check: zoom to 400% in any viewer. If an image is visibly soft on screen at that magnification, it will be soft in print.
- Ask the printer. Most run a preflight as a matter of course and will tell you before anything goes on press.
300 DPI at final placed size is the standard for anything held in the hand. Large-format work viewed from a distance can go lower — a billboard is often 30 DPI, because nobody stands close enough to notice. Below 300 for a brochure is a false economy given the cost of the print run.
Borderless printing
Most home and office printers cannot print to the edge of the paper. It is mechanical rather than a setting: rollers grip the sheet at the margins and the print head cannot reach past them.
Some inkjets offer borderless for photo sizes, and they achieve it by deliberately over-spraying past the edge of the paper — which is why it is often restricted to specific paper sizes and why ink use goes up.
| Situation | What to do |
|---|---|
| Home inkjet, photo paper | Enable Borderless in the printer driver |
| Home printer, plain paper | Usually impossible — design a margin in |
| Office laser | Almost never borderless |
| Commercial print | Supply 3mm bleed; they trim to the edge |
| Getting white edges unexpectedly | Set scaling to Actual Size, not Fit |
That last row catches people constantly. Acrobat's default "Fit" scaling shrinks the page slightly to fit the printer's imageable area, adding a white border to a document that already had none. Set scaling to Actual Size or 100%, then use the driver's borderless option if it has one.
Frequently asked questions
Why will my tri-fold brochure not fold flat?
Because the panels are equal widths. The panel that folds innermost must be about 3mm narrower so it fits inside the other two — otherwise it meets the fold and buckles. Heavier paper needs more allowance.
Which panel is the front cover on a tri-fold?
The rightmost panel of the outside sheet, with the back cover in the middle and the inward-folding panel on the left. Fold a real sheet and number the panels in reading order before laying anything out.
What DPI is my PDF?
A PDF has no single DPI. Each image inside it has an effective resolution equal to its pixel dimensions divided by the size it is placed at, and vector content has no resolution at all. Check individual images with Acrobat's Object Inspector or pdfimages -list.
Why does my image look soft in print but fine on screen?
Probably because it was scaled up in the layout, which lowers effective resolution. A 1200-pixel image is 300 DPI at 4 inches wide and 150 DPI at 8 inches — the same file, half the resolution where it matters.
What resolution do brochures need?
300 DPI at the final placed size for anything held in the hand. Large-format work viewed from a distance can be far lower — billboards are often around 30 DPI — but 300 is the standard for print you read close up.
Why can my printer not print to the edge?
Mechanical limitation: rollers grip the paper at the margins and the head cannot reach past them. Some inkjets offer borderless on photo sizes by over-spraying past the paper edge, which is why it is restricted to certain sizes.
Why is there a white border when I print a full-bleed PDF?
Acrobat's default "Fit" scaling shrinks the page to the printer's imageable area. Set scaling to Actual Size or 100%, then enable the driver's borderless mode if it has one.