KDP Cover Size Calculator

Free KDP Cover Size Calculator

A KDP paperback cover is one single image: the back cover, the spine and the front cover side by side, with a little extra all around for bleed. Its exact width depends on your trim size and on how thick the book is, so two books with the same trim size can need different cover files. This calculator works out the full cover size and spine width from your trim size, page count and paper type, then draws a template you can design on.

The numbers come from Amazon KDP's own cover guidance. Everything runs in your browser, nothing is uploaded and there is no sign-up.

How to use the calculator

1. Pick your trim size. Choose one of the popular sizes or the full list of KDP paperback sizes. Use the trim size you selected in KDP, not the size of your manuscript file.
2. Enter the final page count. Use the page count of your finished interior PDF, including blank and front-matter pages. If the page count changes later, the spine changes too.
3. Choose paper and ink. Cream paper is slightly thicker than white, so the same book gets a wider spine on cream.
4. Download the template. Use the PNG (300 DPI) in tools such as Canva, Photoshop or GIMP, or the PDF in tools such as Affinity or Illustrator. Design on top, then hide or delete the guide layer before you export.

How KDP calculates cover size

According to KDP's paperback cover help page, the full cover is measured like this:

• Cover width = bleed + back cover width + spine width + front cover width + bleed
• Cover height = bleed + trim height + bleed
• Bleed = 0.125 in (3.2 mm) on the top, bottom and outside edges

The front and back panels are each the size of your trim. Only the spine depends on page count.

Spine width by paper type

KDP calculates spine width as page count multiplied by a per-page thickness. These are the values KDP publishes:

Example: a 6 × 9 in paperback with 300 pages on white paper has a 0.676 in spine, so the full cover is 12.926 × 9.25 in, or 3878 × 2775 pixels at 300 DPI.

Spine text: the 79-page rule

KDP says a book needs at least 79 pages to have text on the spine. Below that, the spine is too narrow, so keep it plain or use colour only. When you do add spine text, KDP asks for at least 0.0625 in (1.6 mm) of space from each edge of the spine. The template marks this area with a dashed line when your page count allows spine text.

Safe areas and the barcode

KDP asks you to keep text on the front and back at least 0.125 in (3.2 mm) inside the trim lines and out of the spine area, so nothing important is cut off or wraps around the edge. The template shows these safe areas with dashed blue lines.

If you don't add your own barcode, KDP places an ISBN barcode in a 2 × 1.2 in (50.8 × 30.5 mm) white box in the lower right of the back cover. KDP's barcode help page says a barcode you supply must be that size and placed at least 0.76 in from the bottom of the cover and at least 0.25 in from the spine. Keep that area free of important text and artwork. The yellow box on the template shows it.

Cover file requirements

• One single PDF that contains the back cover, spine and front cover as one image.
• Images at 300 DPI or more. KDP also recommends CMYK colour for print.
• KDP recommends keeping the cover file at 40 MB or less. Files over 650 MB won't convert.

Common cover mistakes

• Using the wrong page count. If you add or remove pages after designing the cover, the spine width changes and KDP will reject the cover. Recalculate after every interior change.
• Forgetting bleed. Artwork must reach the outer edge of the file, including the 0.125 in bleed.
• Text in the danger zones. Titles too close to the trim, or front-cover text running into the spine, can be cut or shifted.
• Spine text on a thin book. Under 79 pages, remove the spine text.
• Exporting with the guides visible. Hide the template layer before you export your final PDF.

Limits of this calculator

This calculator is for KDP paperbacks. Hardcover covers use a different layout with extra wrap and hinge areas, so use KDP's own hardcover template for those. The numbers follow KDP's published guidance at the time we checked it, but KDP can change its specifications, so always confirm with KDP's cover calculator and the previewer before you publish. Your interior PDF also needs to be the right size: if it isn't, our KDP Book Resizer can rescale it to your trim size.

Sources: KDP Help, Create a Paperback Cover and barcode guidance, checked October 2026.

Frequently asked questions

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