Tips and Tricks

Calculate Image Size for Print and eBooks

If you want to create visually captivating books but aren’t sure how to size your images to fit the page or screen properly, you’re in the right place. In this tutorial, we’ll dive into the math behind calculating the perfect image size for your eBooks and print books, ensuring that your masterpiece leaves a lasting impression on your readers. But don’t worry, we also include easy to use calculators!

Whether you’re designing full-page chapter background images using Atticus’s custom theme builder or crafting standalone visuals for your book’s content, our guide has got you covered.

Jump to Full Bleed Image Size Calculator

Jump to In-Chapter Image Size Calculator

Where to Use Images

You can choose one of the pre-formatted themes for your book, but if you’d like to achieve a unique aesthetic, you can set up and save a custom theme in Atticus.

The Background Image will place your image behind the text of your header and, for print versions, the body content of your book. You must size this image to fit the trim of your book, plus bleed for full coverage.

eBooks do not offer full bleed nor will they work well with images behind the body content, so it restricts you to just the header setting for digital versions. 

We’ll show you how to get these calculations in just a minute.

NOTE: When importing images to Atticus, whether for print or eBook, make sure they are always in .jpg or .png format

Full-Bleed-Background-Images print vs eBook preview

Full Page Images

Using Atticus, you can also insert a Full Page image, with bleed, before or after any page in your book.

You can also insert a full page image, within the margins of your book, within any chapter of your book.

As previously mentioned, eBooks do not allow for bleed, but whenever you set a full page image, it will instead fit it to the device it’s being displayed on, within the margins allowed for that specific device.

When you’re making your design decisions, keep in mind that it costs more to print full color images than grayscale images, and for digital publishing, the more images you include, the larger the file size of your ePub. This can increase delivery fees, depending on your distribution method.

How To Calculate Image Size

Image sizing is crucial for authors to ensure their books are printed with a professional finish. By tailoring images to fit the specific dimensions of your book, you’ll avoid having your images stretched, distorted, or pixelated.

Considering factors like trim, bleed, and margins helps to create a seamless layout where images and text complement one another. Properly adjusted trim ensures images don’t get cut off, while accounting for bleed guarantees that images extend to the very edge of the page. Mindful margins prevent important visual elements from being lost or obscured in the binding.

Overall, precise image sizing creates a polished, visually pleasing book that you will be proud of and your readers will rave about.

Trim, Margins, and Bleed

For print versions, the correct size will depend on the trim size of your book. Atticus will extend the image to the very edges of your page if you size the image to incorporate bleed. It helps to understand some basic print formatting terminology:

  • Trim Size: this is the final width and height of your book. The most common trim size for most self-published books is 6” x 9”
  • Margins: are the space inside the trim that creates a safe border within each page so that the text and content of your book is not cut off by the printer or lost to the inner crease of the book
  • Bleed: refers to the amount of space beyond the trim size that is necessary to include in order to ensure all images, particularly background or “full bleed” images, are safe within the boundaries of the final page after it has been cut at the printer 

If you print with KDP, Amazon requires all full bleed PDFs to extend 0.125” beyond the chosen trim size of a book on the top, bottom and outer edge.

To calculate the bleed required for your chosen trim size, use this formula:

  • Single Page Width in Inches: Trim Size Width + 0.125″
  • Height in Inches: Trim Size Height + 0.25″
  • Pixels = inches x ppi

What is PPI?

PPI is pixels per inch. You may also see this referred to as DPI, or dots per inch. For a high resolution image, use 300 ppi

Here is a handy calculator to help.

Calculate Bleed for a Full Page Image

To use the calculator, enter the trim size you will print your book and press Calculate.

Individual Chapter Images

If you are adding an image within a chapter, it will not extend to the very edges of the page, but will rather fit within the margins, similar to your text. To size this properly, you will need to know the trim size of your book and the margins you’ll be using.

To calculate the image size required fit within the margins of your chosen trim size, use this formula:

  • Single Page Width in Inches: Trim Size Width – (Inside Margin + Outside Margin)
  • Pixels = inches x ppi

NOTE: The length of your image will depend on the layout of the image you’re creating, but you should always create it to suit the maximum width calculated to fit within the margins.

Calculate Image to Fit Within Margins

To use this calculator, enter the width of the trim size of your book, and the inside and outside margins. The default margins as suggested by Atticus are set, but you can adjust if your book uses custom margins.

Sizing Images for eBooks

When publishing eBooks, the sizing of your images isn’t such an exact formula, as how your book displays will vary depending on the device it is being read on. That is one of the most brilliant features of eBooks.

In most cases, you can leave your images set for Print, and they will display nicely in eBook format as well, automatically resizing to fit the individuals device.

Atticus does compress eBook files to reduce delivery fees. It does so in a way specifically designed to allow Amazon to further compress, giving you the highest quality image with the lowest overall delivery size possible.

If image quality is more important to your book than delivery fees, it’s best to leave images at the same 300 PPI (pixels per inch) resolution suggested for print books.

However, if lower delivery costs are higher priority, if you have quite a few images in your book, you may want to duplicate it in Atticus to have a separate version for your eBook. You can reduce the resolution to 100 – 200 ppi before importing and that will reduce the output file size.

eBook Cover Images

The one image in your book that you will always design specifically for digital, rather than print, is the cover you upload into Atticus. This cover image will show in eBook devices as the cover in their library or bookshelf and is exclusively for the ePub version of your book.

NOTE: All publishers will require a separate PDF file for the print book cover of your book. It will need to include the back cover, spine, and front cover. You will not upload this or create it in Atticus. It is entirely separate.

For the eBook cover, where you decide to publish will make a difference.

  • KDP Kindle cover size: 2,560 x 1,600 pixels
  • Apple iBooks cover size: 2,400 x 1,600 or a total of 4 million pixels


To sum this all up, by following the guidelines and using the calculators provided in this tutorial, you can confidently create visually captivating books with perfectly sized images for both eBooks and print books.

Whether you’re working with background images, full-page visuals, or images within chapters, these best practices will ensure that your book looks polished and professional.

So, go ahead and unleash your creativity, bringing your unique vision to life as you design and publish stunning books for your audience to enjoy.

Last Updated: 03/30/2023

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