Glossary · Printing & files
What is bleed in printing?
Definition
Bleed: Bleed is extra image area beyond the trim line — typically 0.125" (about 3 mm) — so colour runs right to the edge after the page is cut.
Bleed is the part of a design that extends past the edge where the paper will be cut. Printers cannot trim every sheet in exactly the same place, so if your background colour or image stops precisely at the trim line, small shifts leave thin white slivers along the edge. Extending artwork beyond the trim prevents that.
The industry-standard bleed is 0.125" (one-eighth of an inch, about 3 mm) on each side that touches the edge. For a book cover that means adding bleed on the outer edges of the whole wrap. For an interior page with images that run to the edge, the page size of your PDF grows by 0.125" in width and 0.25" in height (top, bottom and outside edge). Check the platform's current specifications, as a few printers use a slightly different figure.
Bleed is paired with a safe zone: keep important text and faces well inside the trim line, because anything near the edge may be cut off. A text-only novel interior usually does not need bleed at all — only books with full-page images, colour backgrounds or edge-to-edge illustrations do.
The most common upload rejection on print-on-demand platforms is a file with missing or incorrect bleed, so it is worth getting right before you submit.