Books are printed on larger sheets (or wider rolls) and cut down to their final size. The cutting blade can land a fraction of a millimetre away from the ideal line. If your artwork stops exactly at the edge, that tiny variation leaves a thin white sliver. Bleed solves the problem.

Three lines every print file has

  • Trim line — the finished edge of the page, such as 6 x 9 in.
  • Bleed line — outside the trim. Any colour or image that touches the edge must extend to here.
  • Safe line — inside the trim. Text and important details stay inside it.

How much bleed?

North American print-on-demand services typically ask for 0.125 in (3.175 mm) on every outside edge. Many European printers use 3 mm, and some offset printers ask for 5 mm on covers. Check your printer's file guide — and remember that an interior page with bleed only gets it on the outside, top and bottom edges, never at the spine.

For a 6 x 9 in interior with bleed, the PDF page size is therefore 6.125 x 9.25 in: 0.125 in added to the width (outside edge only) and 0.25 in to the height (top and bottom).

Safe zones

Keep text, page numbers, logos and faces at least 0.25 in (about 6 mm) inside the trim. On interiors you also need a larger inside margin (the gutter) that grows with page count, because pages curve into the binding. Our margin calculator shows the minimums by page count and our recommended comfortable margins.

When you do not need bleed

A text-only novel with white margins on every page does not need interior bleed — upload a PDF at exactly the trim size. Add bleed only if any element (a photo, a coloured background, a chapter-opening graphic) touches the edge. Covers almost always need bleed.

Setting up files

  1. Create the document at trim size and add bleed in the document settings (InDesign, Affinity Publisher and Scribus all support this).
  2. Extend backgrounds and edge-touching images fully into the bleed area.
  3. Place guides at the safe zone and keep live text inside them.
  4. Export a PDF that includes the bleed area. Most POD services want no crop marks; some offset printers want them — follow the brief.
  5. Open the PDF and check the page size matches the expected dimensions with bleed.

Common mistakes

  • Adding bleed to the inside (spine) edge of interior pages.
  • Scaling artwork to fit the trim instead of the bleed, leaving white edges.
  • Putting page numbers or captions in the outer 0.25 in, where trimming can clip them.
  • Using a cover template from a different page count, so the spine is the wrong width.