Well, I wish I could say there's a simple, universal sizing system, but unfortunately, there isn't. The differences in book sizes come down to several factors—such as whether it's a UK or US edition, and even variations between different US hardcovers. Ultimately, it all boils down to cost and production preferences.

To make it easier for you, so you don't have to dive down the rabbit hole yourself, we've put together this hopefully clear (and not too confusing) guide.

And of course, we also have to contend with the Imperial vs Metric systems—because why not make things a little trickier, right?

Please note: These sizes are estimates. There's always a small tolerance of a few millimeters in each direction due to the different machines used by publishers, which can affect the final size of the book. It’s just the nature of the publishing world!