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PDF/X-1a

Printing & file preparation

Also called: press-ready PDF, print PDF

A restricted PDF standard for print production: all fonts embedded, all colour in CMYK or spot, no transparency or scripting. It is the safest format to hand a print-on-demand service.

An ordinary PDF can reference fonts it does not contain, mix colour spaces, and carry live transparency — all fine on screen, all sources of surprise on a press. PDF/X-1a forbids those things, so a file that validates against it will print as it displays.

The two requirements that catch self-publishers most often are font embedding and colour space. A font that is installed on your machine but not embedded in the file will be substituted at print time, silently reflowing the page. And artwork built in RGB has to be converted to CMYK somewhere; doing it yourself means you see the colour shift before a reader does.

You do not always have to produce PDF/X-1a — KDP accepts ordinary PDFs and will process them — but conforming removes an entire category of problem that only becomes visible on a physical proof copy.

SmartKDP is not affiliated with, endorsed by, or sponsored by Amazon. Amazon, Kindle, and Kindle Direct Publishing are trademarks of Amazon.com, Inc. or its affiliates.

Related terms

  • DPI

    How many dots of ink per inch an image contains at its printed size. KDP expects 300 DPI for print interiors and covers; screen images at 72 DPI print visibly soft.

  • Proof copy

    A physical copy printed for you to check before publishing. It is marked as a proof and is the only reliable way to see how your file actually prints.

  • Print on demand

    Manufacturing a book only after someone orders it. There is no print run, no inventory, and no minimum quantity — and the per-copy cost is the same whether you sell one or a thousand.

  • Full-wrap cover

    A single file containing back cover, spine, and front cover as one continuous image. It is the format KDP requires for print books, as opposed to a front-cover-only image.