How to set up a paperback cover file for print

A cover for print is one flat sheet that wraps the whole object: for a left-to-right book, 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 many authors commission the artwork before that.

Everything on this page is the geometry of a perfect-bound paperback. Casebound hardcovers are different objects: KDP's hardcover template adds a wrap of about half an inch and hinge allowances the paperback has never heard of, and IngramSpark's case covers take a 0.625-inch wrap rather than ordinary bleed. Dust jackets are wider again. For those formats, use the printer's generated template — not the arithmetic below.

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 and 264 in another needs a spine about 0.08 inches different on KDP’s white paper — and a difference of roughly a hundred pages moves the spine by about a quarter of an inch, which is the kind of error a printer cannot absorb.

Settle the interior, read the final page count off it, then make the cover. Reversing that order is a 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. Platform minimums differ here. KDP permits front- and back-cover text as close as 0.125″ inside the trim; IngramSpark recommends the full 0.25″, though its templates permit 0.125″. As a conservative cross-platform rule, keep anything you need intact — text, a face, a logo — 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. Binding introduces its own placement tolerance, and KDP explicitly asks for 0.0625″ of clear spine on either side of spine text because binding varies. Spine text should be comfortably inside the spine’s own width, and artwork that must line up exactly across the fold will not.

The thresholds for spine text are the printers', and they differ. KDP allows spine text from 79 pages on uploaded covers; IngramSpark allows none below 48 pages. Below those, there is not enough width to hold type a press can reliably place.

The barcode

The barcode is the platform’s job, but the two big platforms do it differently. KDP lets you supply your own compliant barcode or omit it, in which case Amazon places one automatically in the lower-right area of the back cover — a region you should leave quiet either way, because a blurb that ends underneath a barcode is a blurb nobody finishes. IngramSpark’s cover template includes a mandatory barcode, which can be repositioned within the permitted back-cover area; if you cannot supply one, leave at least 1.75 × 1″ clear for it. The platform’s generated template is the simplest way to get the area right.

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 specification is a minimum of 300 DPI at final size, with no hard maximum — it advises keeping images at about 600 DPI or below to avoid unnecessarily large files. A separate KDP page treats anything under 200 DPI as low resolution, which coexists a little awkwardly with its own 300-DPI target.

Other platforms draw the lines elsewhere. IngramSpark specifies 300 ppi for covers and warns that images below 200 ppi may be rejected. Blurb’s BookWright warns below 250 ppi but lets the warning be ignored. A platform’s preferred resolution and its hard rejection threshold are not necessarily the same number, and a guide that gives you one figure per platform has flattened two different facts into one.

Colour

The requirements here are stated, not mysterious — read the specification of the service you are printing with and follow it exactly, checking it on the day rather than trusting a figure from a blog post.

KDP recommends CMYK for print-cover images, strips embedded colour profiles, and warns against mixing colour spaces and spot colours. IngramSpark specifies CMYK for cover files and converts RGB files before printing, with any resulting colour shift the publisher’s responsibility. Blurb’s BookWright accepts RGB, sRGB, CMYK and grayscale images.

The reason to care: screens are additive and presses are subtractive, and a colour you chose on a monitor does not necessarily exist in ink. Conversions shift colour, so letting a conversion happen once, in the pipeline the printer designed, beats converting twice.

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.

Sources

• KDP, Create a paperback cover, Paperback submission guidelines and Format images in your book
• IngramSpark, File Creation Guide, edition 8.24.26
• Blurb, Checking image PPI in BookWright

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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 — and to the spine, and so to the cover built from it.

Common questions

What size should my cover file be?

For a paperback: 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 and paper.

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?

Colour requirements are printer-specific. KDP recommends CMYK for print-cover images and strips embedded colour profiles. IngramSpark specifies CMYK and converts RGB files, leaving any colour shift the publisher's responsibility. Blurb's BookWright accepts RGB, sRGB, CMYK and grayscale. Check the current specification of the service you are actually printing with.

Where does the barcode go?

On the back cover, but the workflow depends on the printer. KDP adds an ISBN barcode automatically in the lower-right area if you do not supply one. IngramSpark's cover template includes a barcode that can be repositioned within the permitted back-cover area. Either way, use the platform's generated template or reserve its specified barcode area before finalising the artwork.

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

It depends on the printer. KDP allows spine text from 79 pages on uploaded paperback covers; its Cover Creator uses an 80-page minimum. IngramSpark allows none below 48 pages. Even above the threshold, check the platform's generated cover template — a spine that technically clears the minimum can still be too narrow for well-set, safely placed type.