Each version of your book that you plan on publishing (e-book / paperback / hardback) requires its own cover file. The format and specifications vary depending on the format:
E-book:
Only the front cover is required.
An e-book cover needs to be saved as a TIFF or JPEG.
Paperback and hardback:
Must include the back cover, spine, and front cover as one image.
Each cover needs to be saved as a single PDF that includes all the necessary parts (front cover, spine and back cover).
Cover creation resources:
If you plan on creating your own covers, more detailed instructions can be found here:
– Creating an e-book cover – https://kdp.amazon.com/en_US/help/topic/G200645690
– Creating a paperback cover – https://kdp.amazon.com/en_US/help/topic/G201953020
– Creating a hardback cover – https://kdp.amazon.com/en_US/help/topic/GDTKFJPNQCBTMRV6
To find the dimensions for your cover, you can use the Print Cover Calculator, which will also give you a template that you can put straight into any appropriate image-editing software: https://kdp.amazon.com/cover-calculator
If you use the Print Cover Calculator, you must be careful to ensure your selections in the calculator match the selections you make later on in the process (trim size, paper quality etc).
Amazon has a very basic built-in Cover Creator tool that can be used as part of the self-publishing process: https://kdp.amazon.com/en_US/help/topic/G201113520
Note – The images and options available in Amazon’s Cover Creator tool are limited and therefore it is difficult, if not impossible, to use it to create a polished and professional-looking book cover.