# Preflight

> Source: https://www.infinitelibrary.ai/glossary/preflight

Last updated: 2026-09-06
Category: Printing & binding
Also called: Preflight check · File check

Preflight is the automated check of a print file — fonts, image resolution, colour, bleed, page size and count — so faults are caught before printing.

## Definition

**Preflight** is borrowed from aviation: the checklist run before take-off. In print it is the inspection of a PDF against the printer's specification before any paper is committed. Software (Acrobat's Preflight tool, Enfocus PitStop, or the printer's own upload system) opens the file and reports every deviation: fonts not embedded, images below 300 dpi, RGB or spot colours where CMYK is expected, missing bleed, a page size that doesn't match the order, a page count that isn't even, hairlines too thin to print, ink coverage too high, transparency that will flatten badly.

A preflight report is not a judgement on the book; it is a list of things that would print wrong. Some printers **normalise** minor issues automatically (converting colour, adding bleed by mirroring), others reject the file and wait.

Running your own preflight before uploading, and reading the printer's report rather than clicking past it, is the difference between a proof that surprises you and one that doesn't.

## In Bindery

Bindery validates its PDFs against Lulu’s own rules — trim, bleed and spine width from the real page count — before anything prints.

## Related

- [Print-ready PDF (PDF/X)](https://www.infinitelibrary.ai/glossary/print-ready-pdf)
- [Embedded fonts](https://www.infinitelibrary.ai/glossary/embedded-fonts)
- [Bleed](https://www.infinitelibrary.ai/glossary/bleed)
- [DPI (dots per inch)](https://www.infinitelibrary.ai/glossary/dpi)
- [CMYK vs RGB](https://www.infinitelibrary.ai/glossary/cmyk-vs-rgb)
- [Turn a PDF Into a Printed Book](https://www.infinitelibrary.ai/tools/pdf-to-printed-book)
- [Photo Book Maker](https://www.infinitelibrary.ai/formats/photo-book-maker)
- [Book Publishing Glossary — 59 Terms Defined](https://www.infinitelibrary.ai/glossary)
- [Bindery — the Claude-powered book studio](https://www.infinitelibrary.ai/bindery)

---

More from Infinite Library, as one map for AI agents: https://www.infinitelibrary.ai/llms.txt