How to set up a book cover file for print

A cover for print is one flat sheet that wraps the whole object: back cover on the left, spine in the middle, front cover on the right, with a margin of artwork all the way round that the printer will cut off. It is not a picture of the book’s front, which is all an ebook cover ever has to be. Authors who have only ever made an ebook cover meet this for the first time at upload, usually in the form of a rejection.

The dimensions are not hard. What makes covers go wrong is that one of them cannot be known until the interior is finished, and almost everyone commissions the artwork before that.

The spine is the reason a cover cannot be made early

The width of a cover is two trim widths plus the spine. The spine is the book’s thickness, and a book’s thickness is its page count divided by how many pages of that paper stack into an inch.

That page count belongs to your manuscript as typeset, not to the manuscript itself. Change the typeface and it moves. Change the type size, the leading, the margins, whether chapters open on a right-hand page. Each of those moves it, sometimes by twenty pages or more. A book that runs to 300 pages in one design runs to 264 in another, and the two need covers that differ by nearly a quarter of an inch across the spine.

Settle the interior, read the final page count off it, then make the cover. Reversing that order is the single most common way to pay a designer twice.

Paper matters as much as page count. KDP's cream stock runs 400 pages to the inch against white's 444, so the same book is about 11% thicker on cream. Choosing cream after the cover is drawn is the same mistake in a different coat.

Our spine width calculator does the arithmetic and gives you the full cover dimensions alongside it.

The full sheet, and how to size it

Once you have the spine, the rest is addition:

• Width = trim width × 2 + spine width + 0.25″
• Height = trim height + 0.25″

The 0.25″ in each is bleed: 0.125″ on each of the four outer edges. For a 300-page 6 × 9 book on white paper, the spine is 0.676″ and the cover file is 12.926 × 9.25 inches.

Set the artboard to that size and place the spine centrally. Everything to its left is the back cover, everything to its right is the front.

Bleed is not the same as it was in the interior

This trips up authors who have just finished setting the inside of the book, because the rule genuinely differs between the two.

	Bleed on top, bottom, outside	Bleed on binding edge
Interior pages	0.125″ / 3.2 mm	None
Cover	0.125″ / 3.2 mm	Not applicable — the cover has no binding edge

The interior takes no allowance at the gutter because that edge is glued into the spine and never meets a blade. A cover is trimmed on all four sides, so it takes the allowance everywhere. If any interior page bleeds, incidentally, the whole interior file must be set up for bleed. It is not a per-page choice.

What has to stay away from the edges

Two separate margins matter, and they protect against two different things.

The trim margin. Cutting is accurate to a tolerance, not to a line. Anything you need intact, whether text, a face, a logo or a border, should sit at least 0.25″ inside the trim edge. Borders are the worst offenders: a frame that sits 3 mm from the edge on your screen will be visibly thicker on one side than the other in print, because the sheet shifted by a millimetre. A border that close to the trim advertises the tolerance instead of hiding it.

The spine margin. The fold is even less precise than the cut. Spine text should be comfortably inside the spine’s own width, and artwork that must line up exactly across the fold will not.

Below 100 pages, KDP and IngramSpark both reject covers with any text on the spine. There is not enough width to hold type that a press can reliably place.

The barcode

Print-on-demand platforms add the barcode themselves, in the lower right of the back cover. You do not supply one, and you should not design something there you need to be seen: a blurb that ends underneath it, or artwork with detail in that corner. Leave the area quiet.

Resolution, and the difference between advised and refused

Cover artwork is print artwork, and print wants far more pixels than a screen does. KDP’s stated minimum is 300 DPI at final size, with 600 DPI recommended as a practical ceiling.

Those two numbers are not the same kind of number, and the distinction is worth internalising because it runs through every platform specification you will read. 300 DPI is written as a minimum. 600 DPI is a recommendation, and going past it does not get a file refused. It makes it large and slow to process. A separate KDP page treats anything under 200 DPI as low resolution.

Other platforms draw the line elsewhere. IngramSpark recommends 300 DPI and rejects below 72. Blurb warns at 250 and prints anyway. A guide that gives you one figure per platform has flattened two different facts into one, and the flattening is what causes authors to either panic about a file that would print perfectly well or ship one that gets refused.

Colour

This is the part where general advice ages badly, so treat what follows as the shape of the problem rather than as a setting to copy.

Screens are additive and presses are subtractive. A colour you chose on a monitor does not necessarily exist in ink, and the deep saturated blues and vivid oranges that look best on a listing page are the ones most likely to come back muted. Converting between colour spaces is lossy, and converting twice, once by you and once by the printer’s pipeline, is where covers arrive looking washed out.

So: read the colour specification your platform publishes, follow it exactly, and check it on the day rather than trusting a figure from a blog post. Where a platform does not state a requirement, and several do not, that silence is itself worth knowing about, because it means the safest thing is to change as little as possible and let their pipeline do the conversion once.

The order that works

1. Finish the interior. Every typographic decision, settled.
2. Read the final page count.
3. Choose the paper stock, and do not change it afterwards.
4. Calculate the spine, and from it the full cover size.
5. Now commission or draw the artwork, on an artboard that size.
6. Check the trim margin, the spine margin and the barcode area before export.

Steps one to three are the ones people skip, and they are the ones that cost money.

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In Nueel, the page count is a fact about your book that updates as you work, so the number you need for the spine is on screen rather than being something you find out at upload. Change the design and you see immediately what it does to the length, including whether it pushes you over or under the threshold where a spine can carry its own title.

Common questions

What size should my cover file be?

Two trim widths, plus the spine width, plus 0.25 inches of bleed for the width. For the height, the trim height plus 0.25 inches. A 300-page 6 × 9 book on white paper comes to 12.926 × 9.25 inches. The spine is the part that varies, and it comes from your final page count.

Why is my cover the wrong size after I finished the book?

Because the spine width follows the page count, and the page count follows every typographic decision in the interior. Changing the typeface, the type size, the leading or the margins changes how many pages the book runs to, which changes how thick it is. A cover commissioned before the interior is settled will need remaking.

Does the cover need bleed on all four sides?

Yes. A cover is trimmed on all four outer edges, so KDP asks for 0.125 inches on each. The interior works differently. Its binding edge is never trimmed, so KDP asks for bleed on the top, bottom and outside edges only.

Should my cover be CMYK or RGB?

Follow the specification your printer publishes rather than a general rule, and check it on the day. Converting between colour spaces shifts colour, and a conversion done twice, once by you and once by the printer, is where covers come back looking flat.

Where does the barcode go?

On the back cover, and print-on-demand platforms place it themselves. Leave the lower right area of the back cover clear of anything you need to be seen, and do not supply your own barcode unless you are certain the platform expects one.

Can I put text on the spine of a short book?

Below 100 pages both KDP and IngramSpark reject covers with spine text, because the spine is too narrow to hold legible type. If your book is close to the threshold, a slightly larger type size or more generous leading pushes the page count over it.