Children book authors are better off using trim sizes in pixels than inches when it comes to creating illustrations. Here is how they convert.

Do you know your available trim sizes in pixels? There’s plenty to think about when creating a children’s picture book. Illustrations will likely be the most expensive and time consuming part of the process, but also the most important. After all, what is a picture book without pictures? When you are deciding on a book size it’s important to prepare smartly. If you are looking to self-publish, then print-on-demand services will be a key part of your business strategy. And print-on-demand services offer only a small number of book trim sizes.

The benefit of a print-on-demand service – such as Kindle Direct Publishing, KDP or IngramSpark – is that there is no initial investment. Books are printed when they are ordered. It’s true, the production cost is a bit higher and the quality isn’t as good as a traditional offset printer. However, you don’t have to order in bulk, find room to store hundreds (if not thousands) of books or manually post them to buyers.

So if you’re looking to self-publish on a budget, you should consider choosing a book size that matches those available at a print-on-demand service. Amazon’s trim sizes are a good place to start. It is your most likely avenue for global sales, after all. However, Amazon’s primary concern is not children’s picture books – it is normal text books. As a result, the information Amazon supplies - and indeed the trim sizes themselves - aren’t optimised for children’s picture book creators. They don’t show trim sizes in pixels.

Children’s book trim sizes in pixels

Below you will find a table that details the main print-on-demand trim sizes available through Amazon, KDP and Ingramspark. The difference with this table is that you can also get that trim size in pixels at a print-ready 300 dpi resolution. So why is this helpful?

Artists, illustrators and designers generally work in pixels, not inches. When commissioning art, you will need to brief the artist on what size canvas they should use. The canvas will be the trim size in pixels. All the key imagery must be presented within this canvas to appear on the page. Also, for an image to display without any pixilation in print, it needs to be provided at 300 dots-per-inch (dpi). So you want the image to be a minimum of 300dpi when scaled to the maximum trim size. We have a whole article on dpi, if you need to know more.

Four other things to consider with book trim size in pixels:

1. If you are doing an image that will be full page, then you will need to add bleed. Bleed refers to a part of the image that extends past the trim size of the page. This is provided to account for slight movements of the printing plate, ensuring that you don’t end up with an ugly white line at the edge of your image. I have provided a pixel size with bleed in the below table.
2. These trim sizes refer to a single page in the book. So if you want an image to spread across two pages, you will need to adjust the canvas size to accommodate.
3. The cover will be slightly wider again. This is because the cover will wrap around the edge of the book and over the bind. How much wider will depend on the page number, but is usually 100 pixels or less. So consider that when commissioning your cover art.
4. Personally, I get all my art made at least double the minimum pixel dimensions required for my desired trim size. I then scale it back to the smaller size required to fit the book. This gives more flexibility in design. I can zoom in, for example, without reducing the dpi below 300.

Where to next?

Old Mate Media offers both art and design services, with more information about the process. You can also read our full, step-by-step guide to creating a children’s picture book. In terms of the design process, you may also find value in our guide to text layout.