Book Cover Resizer (KDP) – everything it can do:

3D Book Mockup Generator

Turn your cover into a 3D book, an eBook on a tablet and phone, and ready-to-post promo images.

Loading the book cover tool…

3D Book Mockup Generator at a glance

Price
Free
Account
Not needed
Watermark
None
Privacy
Files are processed inside your browser and are never uploaded.
Works on
Windows, Mac, Linux, Android and iPhone – in any modern browser
Install
Nothing to install
3D book in secondsA realistic paperback with spine, page edges and shadow – on a transparent background for your website or Amazon A+ content.
Posts for every networkInstagram post and story, Facebook/X banner and Pinterest pin with your headline, in colours taken from your cover.
One-click publisher packEvery store cover size and every mockup in one ZIP.

How to use 3D Book Mockup Generator

  1. Choose your front cover picture.
  2. Pick the spine colour, thickness, headline and background.
  3. Download each image or all of them in one ZIP.

Why KDP rejects covers

Most rejected covers have one of four problems: the size is wrong (a paperback cover must include the back, the spine and the front plus 0.125″ bleed on every outside edge), the spine width does not match the page count and paper, the picture is below 300 DPI, or text sits too close to the edge and could be cut off. This tool fixes all four.

eBook cover sizes by store

StoreSize made by this toolNotes
Amazon Kindle (KDP)1600 × 2560 pxHeight to width 1.6 : 1, JPG or TIFF, RGB, under 50 MB
Apple Books1600 × 2400 pxAt least 1400 px wide
Kobo Writing Life1600 × 2400 pxJPG or PNG
Google Play Books1600 × 2560 pxAt least 640 × 1024 px
Draft2Digital1600 × 2400 pxTall rectangle
IngramSpark eBook1600 × 2560 pxJPG only, RGB
Audiobook (ACX / Audible)2400 × 2400 pxSquare

Stores update their rules from time to time – check the store’s help page if a cover is rejected. If your picture is a different shape, choose to fill (crop a little), fit it with a blurred or plain background, or stretch it. Amazon suggests a thin grey border for white or very light covers so they do not disappear on a white page – the tool switches it on for you when your cover is light.

Paperback cover size: how it is worked out

Full cover width = bleed + back cover + spine + front cover + bleed. Height = bleed + trim height + bleed. KDP uses 0.125″ (3.2 mm) bleed. The spine width depends on the number of pages and the paper:

For example, a 6 × 9 inch book with 300 pages on white paper has a spine of 0.676″ and a full cover of 12.926 × 9.25 inches – 3878 × 2775 pixels at 300 DPI. KDP allows text on the spine only when the book has more than 79 pages; the tool tells you when that applies.

Front cover only, or a full cover you already have

Have only the front? The tool builds the back and spine in a colour taken from your front cover, adds your blurb and the title and author on the spine, and keeps the barcode area (2 × 1.2 in, bottom right of the back) free. The bleed is filled by mirroring the edges of your picture, so nothing important is cut off. Already have a full wrap from a designer? Choose “A full cover” – it is resized to the exact size, and you are warned if its shape suggests a different page count.

Any picture at 300 DPI

Need interior pictures for a picture book, a print at 8 × 10 inches or an A4 poster? The third tab makes any number of pictures the exact print size at 300 DPI (or 150 or 600), with an option for KDP interior bleed (+0.125″ width, +0.25″ height). Save them as JPG, PNG or one PDF.

Hardcover and other printers

Hardcover covers wrap around the boards and use different measurements. Choose “Other size / other printer” and “Type the spine width myself”, then enter the sizes from the printer’s own cover calculator – for KDP hardcovers, from the KDP cover template.

More tools for publishers

Frequently asked questions

Is the 3D book background transparent?
Yes. The 3D paperback is a PNG with a transparent background, so it can be placed on any colour or photo.
Can I change the text on the posts?
Yes. Type your own headline and second line – for example “Out now” and “Available on Amazon and Kobo”. Urdu and Arabic text work too.
Is my cover uploaded anywhere?
No. Your pictures are resized and the PDF is made on your own phone or computer. Nothing is sent to a server, so unpublished covers stay private.
Can a small picture really become 300 DPI?
The file will be 300 DPI and the exact size, but enlarging cannot add detail that is not in the original. The tool tells you how much your picture is enlarged: up to about 1.5× usually prints well; more than that may look soft. For the sharpest result, start from the largest version of your design.

More free tools