What it means
Bleed is the margin of extra image or colour printed beyond the trim line and then cut away. Guillotines are accurate only to about 1/16 in (1.5 mm), so a background that stopped exactly at the trim would sometimes leave a hairline of white paper. Extending it past the edge guarantees a clean bleed-off.
The standard allowance is 0.125 in (3 mm) on each side. A 6 × 9 in page with bleed is therefore submitted as 6.25 × 9.25 in, and a full cover wrap adds 0.125 in all the way around. Content that must not be cut — text, faces, logos — should stay inside a safe zone at least 0.25 in (6 mm) in from the trim.
Bleed applies to interiors as well as covers: photo books, cookbooks and picture books with full-page images need it on every page, whereas a text-only novel usually needs none and is printed with plain white margins.
In Bindery
Bindery’s print files are validated against Lulu’s own rules — trim, bleed and spine width — before anything prints, so a missing bleed is caught in the studio, not at the press.
Make the book, not the checklist
Describe a book or upload a manuscript. Bindery writes with you, typesets in LaTeX, sizes the spine from the real page count and produces printer-validated files — the watermarked proof is always free.
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