Choosing a Trim Size and Binding for Your Book

Trim size is the finished dimensions of your book. Binding is how the pages are held together. You choose both before formatting, because every page of your interior file is built to those measurements, and changing your mind afterwards means laying the book out again.

Trim size: follow your genre, then stop thinking about it

Readers hold hundreds of books before they hold yours, and they have absorbed what each kind of book feels like without ever noticing. A novel in an unfamiliar shape reads as self-published before a single word is read, and not in a flattering way.

So the rule is simple. Go to a shelf of books like yours, in a shop or on your own shelf, and measure three of them. Match that. The conventions differ by category: literary and commercial fiction sit in one range, mass market genre paperbacks in a smaller one, non-fiction and memoir tend larger, poetry chapbooks smaller and often squarer, and children's picture books follow their own rules entirely.

There are two reasons to break convention, and they are both good ones: an art or photography book that needs the space, and a poetry collection where the shape is part of the work. Otherwise, the interesting choice costs you more than it earns.

Page count decides more than you expect

Once trim size is set, page count does most of the remaining work.

It sets your spine width. The spine is a calculation from page count and paper thickness, and the cover file has to be built to it exactly. Get it wrong and the title creeps around onto the front. This is the most common reason a cover file is rejected.

It drives your print cost. Paper is the bulk of the expense, so page count is the biggest lever you have on what a copy costs to make, and therefore on what you earn.

It rules some bindings out. A book can be too thin to have a spine printed at all, and too thick to bind in some formats.

Note that trim size and page count trade against each other. The same manuscript set in a smaller trim runs to more pages. Smaller pages are not automatically cheaper.

The five bindings, and when each is right

• Paperback. The default, and correctly so. Cheapest to print, what most readers expect, and the format that carries a genre novel.
• Hardcover. Costs more to make and sells for considerably more, so the margin per copy is usually better, not worse. Right for gift editions, special editions, and non-fiction that wants to look like a reference.
• Saddle stitch. Folded and stapled through the spine. The correct choice for thin books: chapbooks, zines, short poetry collections, programmes. Cheap and appropriate, not a compromise.
• Coil bound. Lies flat when open, which matters enormously for workbooks, cookbooks, sheet music and manuals. Nobody wants to hold a recipe open with their elbow.
• Linen wrap. A cloth-covered hardcover, usually with foil stamping. This is a keepsake edition. It works when you have an audience that already wants your book as an object, so it suits a special edition or a crowdfunded run better than a debut.

A practical order of decisions

1. Measure three books in your genre and take the trim size from them.
2. Set your interior to that trim and find your real page count.
3. Price it with that page count before you format properly. If the number does not work, this is when to change it.
4. Only then build the cover, to the spine width your final page count produces.

Most authors do these in the wrong order and discover the cost problem after the book is laid out, when fixing it means starting the interior again.

Compare all five bindings side by side, download a free template built to the exact trim you have chosen, and price it before you format a single page.