Last reviewed by Robert Prime — September 2026
Quick Answer: Brief the reader, not the design. Give your designer the final page count, trim size, paper stock, blurb, genre, and three covers you like plus one you don’t. On specs: KDP needs one flat PDF containing back, spine and front, 300 DPI, 0.125" bleed, CMYK, 7pt minimum type. Spine width is page count × 0.0025" on cream paper, and spine text only prints above 79 pages. Do not commission the wrap until the page count is final.
Below: the brief that works, and the specifications that get files rejected.
Table of Contents
- Brief the reader, not the design
- What to send, in full
- What wastes everyone’s time
- The paperback specifications
- Hardcover is a different shape
- The ebook cover
- The font trap
- Where KDP contradicts itself
- Frequently asked questions
Brief the reader, not the design
The most common brief a designer receives describes a picture: a lighthouse, a woman in a red coat, fog. The most useful brief describes a person: who reads this, what else they read, and what promise the cover has to make them.
The reason is practical. A designer can render your lighthouse perfectly and still produce a cover that signals the wrong genre, which is the one failure that actually costs sales. Genre signalling is a set of conventions readers have learned — typography weight, palette, the amount of the frame the title takes — and a designer who knows your genre is applying a body of knowledge you probably do not have.
So the sentence that unlocks the best work is not “I picture a lighthouse.” It is “This is for people who read Elly Griffiths and want the same feeling.”
What to send, in full
Everything a competent designer needs fits on one page:
| Why it matters | |
|---|---|
| Final page count | Spine width is calculated from it. This is not optional |
| Trim size | 4–8.5in wide × 6–11.69in tall are KDP’s bounds for the cover calculator |
| Paper stock (white / cream / colour) | It changes the spine multiplier |
| Blurb | The cover’s job is to earn the blurb a reading |
| Genre, as a reader would say it | Not “literary thriller with speculative elements” |
| Three covers you like, one you don’t | The “don’t” is more useful than the three |
| Series? | Changes the whole approach — a system, not a cover |
| Your name as it appears | Pen name, and whether it is bigger than the title |
| Any fixed elements | Series branding, an imprint logo, an award sticker |
If we are formatting your interior too, you can skip the first three — we take them from the file, which is the point of doing both in one place. It removes the single most common source of a wrong spine.
What wastes everyone’s time
Sending a design you made in Canva. It anchors the designer to your layout and you end up paying for a tidy-up of your own idea rather than their expertise.
“I’ll know it when I see it.” This guarantees extra rounds. If you cannot name what you want, name three books that have it.
Committee feedback. Six opinions produce a cover that is nobody’s. Choose one decision-maker.
Feedback on taste rather than fit. “I don’t like green” is a fact about you. “Green reads as cosy and this is a hard thriller” is a fact about the market, and it is actionable.
Commissioning before the manuscript is final. Covered below, and it is the expensive one.
The paperback specifications
All from KDP’s own paperback cover requirements, read 19 September 2026.
The file. One single PDF containing back cover, spine and front cover as one image. Not three files. Not a layered PSD.
Resolution and colour. Minimum 300 DPI. CMYK colour space. Maximum file size 650MB.
Bleed. 0.125" on the top, bottom and outside edges.
Type size. Minimum 7pt, which catches small print on back covers.
Spine width — the arithmetic that governs everything:
| Paper | Multiplier |
|---|---|
| Black-and-white, white paper | pages × 0.002252" |
| Black-and-white, cream paper | pages × 0.0025" |
| Premium colour | pages × 0.002347" |
| Standard colour | pages × 0.002252" |
Spine text prints only on books of more than 79 pages, and needs 0.0625" clearance either side.
The consequence to plan around: a 300-page cream-paper book has a 0.75" spine. Add 40 pages in a final edit and it becomes 0.85". Since the wrap is one flat file, that is not an adjustment — it is a rebuild. Lock the interior, then commission the wrap. Authors who do it the other way round pay for the cover twice, and it is the single most common sequencing mistake in self-publishing.
KDP publishes a cover template calculator that generates a PDF and PNG template for your exact dimensions. Use it, or give your designer the inputs and let them.
Hardcover is a different shape
Hardcover is not a bigger paperback, and a designer who has only done paperbacks can get this wrong.
- 0.51" wrap on each edge — this is fold-around, not bleed, and it disappears inside the case
- 0.4" hinge channel where the cover meets the spine, which artwork must survive
- Text kept 0.635" from the edge
- Barcode area 2" × 1.2", positioned 0.76" from the bottom
Anything important placed in the wrap or hinge is gone once the book is bound.
One figure we are not giving you: the hardcover spine formula. Every third-party calculator on the internet publishes one. It appears on no KDP page we could find — KDP directs you to its calculator instead. So we direct you there too, rather than repeat a number we cannot source.
The ebook cover
A completely separate file, and much simpler:
- 2560 × 1600 pixels ideal
- 1000 × 625 pixels minimum
- 1.6:1 aspect ratio
- RGB colour
- TIFF or JPEG
Note the aspect ratio differs from your paperback’s front cover proportions, so the ebook version is a re-crop or a re-layout, not an export. This is why “ebook cover” and “print wrap” are priced separately almost everywhere.
The font trap
KDP’s own wording, and it is the clearest statement of a problem most authors never think about:
“Unembedded fonts or fonts prohibiting commercial embedding prevent printing.”
Font licences are not all alike. Plenty permit use in a design but prohibit embedding in a distributed file — which is exactly what a print PDF does. The result is not a legal letter years later; it is a file that will not print, now.
Ask your designer which fonts they used and whether the licence permits commercial embedding. A professional will have the answer ready. If nobody can answer it, that is the answer.
Where KDP contradicts itself
Worth knowing so you do not waste an afternoon reconciling it. On ebook covers, KDP’s documentation states both 72 dpi and 300 PPI on the same page, and gives the maximum file size as “less than 50MB” on one page and “5MB or fewer” on another.
We have not silently picked one. Build to the stricter figure in each case — 300 PPI and the smaller size cap — and you satisfy both readings.
Frequently asked questions
How long should a cover take?
Five to seven working days from brief to print-ready files is normal for a straightforward cover, longer for illustration. We found no survey behind any of the timelines quoted online, so treat specific claims — including ours — as practice rather than data.
Can the designer start before my manuscript is finished?
They can start the front cover, which does not depend on page count. They cannot finalise the wrap. Split it that way if you are in a hurry.
What files should I insist on?
The print PDF, the ebook JPEG at the dimensions above, and — the one people forget — the layered source file. Without it you cannot change anything later, and the spine will eventually need changing.
Do I need a different cover for hardback?
Yes. Different geometry, different wrap, a hinge channel. The artwork can be the same; the file cannot.
How small does my cover need to work?
Small enough to read as a thumbnail in search results. We could not verify Amazon’s actual rendered pixel size at source — the figures circulating come from designer blogs, not Amazon — so the honest test is practical: shrink your cover until it is about the size of a postage stamp on your phone. If the title is unreadable, so is the cover.
Should I put review quotes on the front?
Only if the quote is from someone your reader recognises. Otherwise it competes with the title at thumbnail size, where you have very little room to lose.
Final thoughts
Most cover problems are not taste problems. They are sequencing problems — a wrap commissioned before the page count settled — or licensing problems, like a font that cannot be embedded.
Get the brief right by describing the reader, get the page count locked before the wrap is built, and insist on the source file. That is most of it.
If you would rather the interior and the cover came from one place so the spine cannot drift, we do both — the £199 wrap is built to the page count of the interior we format.
Read next
This is one of four guides on getting a cover made. The others cover what a cover actually costs, tier by tier with real published prices; premade against bespoke, and the spine arithmetic that breaks a premade wrap; and cheap, AI or professional, including what Amazon makes you declare. If you only need the number, you can work out your spine width from your page count in a few seconds.
— Robert publishing.co.uk
Who wrote this. I am Robert Prime. I run publishing.co.uk, a UK formatting and self-publishing service, which means I spend my week inside KDP's actual upload screens and rejection emails rather than reading about them. I was a guest on the Alliance of Independent Authors' Self-Publishing Advice podcast in July 2026, talking about how AI engines find books. Every price and specification on this page carries the date I read it from the source, and where I could not verify something I have said so on the page rather than filled the gap. If you find something wrong here, tell me and I will correct it and say that I have.
