What does print-ready actually mean?

That the file can go to press without anyone editing it. In practice: every font embedded, pages as single sequential pages rather than spreads, bleed present on the edges that get trimmed, images at sufficient resolution, and the PDF conforming to whatever standard the printer names. Print-on-demand services process files as received and do not preflight them for you.

Why do my fonts need to be embedded?

Because the printer's system does not have your fonts. An unembedded font is substituted, which changes the line breaks, which changes the page count, which changes the spine width your cover was built for. Both KDP and IngramSpark reject files with unembedded fonts outright, which is the better outcome; a silent substitution would be worse.

Should I export single pages or spreads?

Single pages, always, in sequential order. IngramSpark states that files sent as spreads will be rejected, and KDP requires the same. A spread is a way of viewing a book, not a way of manufacturing one, because the two halves of a spread are printed on different sheets.

Which edges need bleed?

For an interior, three: top, bottom and outside. The binding edge is never trimmed, so it takes no bleed, and adding it there pushes your content out of position. Both KDP and IngramSpark specify 0.125 inches, or about 3.2mm, on those three edges. A cover is different: it is trimmed on all four outer edges and needs bleed on all of them.

What image resolution do I need?

300 DPI at final printed size is the working standard for photographs and greyscale images, and 600 DPI for 1-bit line art. The refusal threshold is usually lower and stated separately: IngramSpark rejects images below 72 DPI. An image between the two prints poorly but is not refused, which is why the two numbers should not be collapsed into one.

Why did my proof come back with grey text instead of black?

Usually because an ICC profile was applied to text that should have been 100% black. IngramSpark warns about exactly this: profiles applied to 100% black text often convert to a percentage of grey, which prints as washed-out body text. For text at 24 point and below, use 100% black only.

The print-ready PDF checklist

Print-on-demand services process files as received. They do not preflight your book, they do not fix it, and in most cases they do not look at it. What they do is run it through a manufacturing process that either works or produces something you paid for and cannot sell.

So the check has to happen before the upload. Here is what to check.

1. Every font is embedded

The printer’s system does not have your fonts. If they are not inside the file, something else gets substituted, and a substituted font changes the line breaks, which changes the page count, which changes the spine width the cover was built for.

Both KDP and IngramSpark reject files with unembedded fonts. That is the good outcome — a silent substitution would be far worse.

To check in Acrobat: File → Properties → Fonts. Every font listed should show (Embedded) or (Embedded Subset). Anything without one of those tags is not in the file.

Acrobat's default "Standard" preset does not embed the base 14 fonts, which is enough on its own to get a file rejected. This catches people who exported correctly from a design application and then re-saved the PDF.

2. Single pages, not spreads

Submit the interior as sequential single pages: page 1, page 2, page 3.

A spread is a way of looking at a book, not a way of manufacturing one — the two halves of a spread are printed on different sheets of paper. IngramSpark states that files sent as spreads are rejected for a corrected submission, and KDP requires the same.

In InDesign this is a checkbox at export. It is off by default, and turning it on is a mistake nobody makes deliberately.

3. Bleed on the right edges

If anything in the book runs off the edge of a page, the file needs bleed: extra artwork beyond the trim line that gets cut away, so a slight variance in trimming does not leave a white sliver.

For an interior, that is three edges: top, bottom and outside. The binding edge is never trimmed. Adding bleed there does not add safety; it shifts your entire text block off centre.

	Bleed	Edges
Interior	0.125″ / 3.2mm	top, bottom, outside
Cover	0.125″ / 3.2mm	all four

If nothing runs off the edge, you do not need bleed at all, and a smaller outside margin minimum usually applies.

4. Margins that account for the binding

The inside margin is not the same as the others, because a thicker book curves more sharply into its binding. KDP enforces a table that grows with the page count, from 0.375″ under 150 pages to 0.875″ past 700. IngramSpark recommends a minimum of 0.5″ on all sides.

The distinction between enforced and recommended matters: one gets your file rejected, the other produces a book that is merely hard to read. Both are worth satisfying.

Printing also carries a physical tolerance. IngramSpark allows 1/16″, about 2mm, of variance on every book it prints. Anything you need to be seen should sit well inside the trim, not near it.

5. Images at printing resolution

300 DPI at final printed size is the working standard for photographs and greyscale. 600 DPI is usual for 1-bit line art, which has no intermediate tones to hide the stepping.

“At final printed size” is the part that catches people. A 1000-pixel-wide image is 300 DPI at 3.3 inches and 100 DPI at 10 inches. Enlarging it in the layout lowers its effective resolution.

The refusal threshold is separate and lower — IngramSpark rejects images under 72 DPI. An image between 72 and 300 prints poorly and is not refused, which is exactly why the recommendation and the refusal should not be collapsed into one number. Being told “rejected” about something that prints teaches you to ignore the whole report.

Nothing can be done about a low-resolution image after the fact. The pixels are not there, and enlarging invents detail that was never captured.

6. Colour, if the book has any

For a colour interior, images should be CMYK, and there is a ceiling on how much ink can go on the paper: 240% total CMYK value at IngramSpark. Past that, ink builds up, detail is lost, and the sheet can fail to dry properly.

A rich black is not four channels at 100%. IngramSpark recommends 60C / 40M / 40Y / 100K, which comes to 240%. Building anything in registration — 100% of all four — is a mistake.

For body text at 24 point and below, use 100% black only. This is the single most common cause of proofs that come back with grey-looking text: an ICC profile applied to black text converts it to a percentage of grey, and it prints exactly as washed out as it sounds.

For a black-and-white interior, convert images to greyscale yourself. RGB and CMYK images are converted at print time, and a conversion you did not control is a conversion you cannot correct.

7. The PDF standard your printer names

IngramSpark requires PDF/X-1a:2001 or PDF/X-3:2002 conformance for both interiors and covers. KDP does not name a PDF/X standard for interiors.

Follow the specification your printer publishes, and check it on the day. These requirements change, and a figure from a blog post — including this one — is a starting point rather than an authority.

8. No crop marks

Do not include crop, printer or registration marks. Print-on-demand workflows do not need them, and marks left in a file can end up printed on the finished book.

The check, in order

Fonts: all embedded, verified in the file’s properties.
Pages: single, sequential, no spreads.
Bleed: three edges on the interior, four on the cover, or none if nothing bleeds.
Margins: inside margin matched to the final page count.
Images: 300 DPI at printed size, nothing under the refusal threshold.
Colour: CMYK, under 240% total ink, body text at 100% black.
PDF standard: whatever the printer names, checked today.
No crop marks.
Cover built last, from the final page count.

Every item above is cheap to check and expensive to miss, and they interact: the gutter depends on the page count, the page count depends on the typesetting, and the cover depends on both. A book usually fails on the last one, because the cover was commissioned first.

Nueel checks a document against the published requirements of the service you are exporting for before it exports, and where the requirement determines the fix — a bleed value, a margin — it offers that fix rather than only naming the problem. The requirements are kept as dated records of each provider’s own specification, so a rule that changes is an edit to a record rather than a guess.

Common questions

What does print-ready actually mean?: That the file can go to press without anyone editing it. In practice: every font embedded, pages as single sequential pages rather than spreads, bleed present on the edges that get trimmed, images at sufficient resolution, and the PDF conforming to whatever standard the printer names. Print-on-demand services process files as received and do not preflight them for you.
Why do my fonts need to be embedded?: Because the printer's system does not have your fonts. An unembedded font is substituted, which changes the line breaks, which changes the page count, which changes the spine width your cover was built for. Both KDP and IngramSpark reject files with unembedded fonts outright, which is the better outcome; a silent substitution would be worse.
Should I export single pages or spreads?: Single pages, always, in sequential order. IngramSpark states that files sent as spreads will be rejected, and KDP requires the same. A spread is a way of viewing a book, not a way of manufacturing one, because the two halves of a spread are printed on different sheets.
Which edges need bleed?: For an interior, three: top, bottom and outside. The binding edge is never trimmed, so it takes no bleed, and adding it there pushes your content out of position. Both KDP and IngramSpark specify 0.125 inches, or about 3.2mm, on those three edges. A cover is different: it is trimmed on all four outer edges and needs bleed on all of them.
What image resolution do I need?: 300 DPI at final printed size is the working standard for photographs and greyscale images, and 600 DPI for 1-bit line art. The refusal threshold is usually lower and stated separately: IngramSpark rejects images below 72 DPI. An image between the two prints poorly but is not refused, which is why the two numbers should not be collapsed into one.
Does my PDF need to be PDF/X?: It depends on the printer. IngramSpark requires PDF/X-1a:2001 or PDF/X-3:2002 conformance. KDP does not name a PDF/X standard for interiors. Follow the specification your printer publishes rather than a general rule, and check it on the day rather than trusting a figure from a blog post.
Why did my proof come back with grey text instead of black?: Usually because an ICC profile was applied to text that should have been 100% black. IngramSpark warns about exactly this: profiles applied to 100% black text often convert to a percentage of grey, which prints as washed-out body text. For text at 24 point and below, use 100% black only.