How to choose the right trim size for your book
Keep reading for the low-down on book trim sizes and how to choose the best one.
Why is the trim size of a book important?
The size of your book will affect how it looks and feels. For example, is it the kind of book that you can tuck in a suitcase for a holiday read or in your bag for the commute to work? Or is it a gift book, pocket-sized for keeping as a memento?
Will your book sit nicely on a shelf with others in a library or look professional on display in a bookshop? Or would they have difficulty trying to find somewhere to store your book because it doesn’t physically fit in alongside others in its genre – potentially putting booksellers and libraries off stocking it?
The readers’ expectations are another important factor in deciding your trim size.
If your readers expect a particular type of book to be formatted in a certain way, it might be off-putting for them to see your title looking different from others in the same genre – humans tend to be creatures of habit!
So, the size of your book influences a reader’s experience and also its saleability, with a familiar trim size being more marketable. It speaks volumes about what type of book it is.
Trim size and costs
The trim size you choose also influences factors such as pricing and printing costs. For instance, the size of your book determines the number of words you can fit on a page, which in turn affects your page count – and more pages in a book will increase the cost of printing it.
You might notice that some standard paperback books have font so small it’s difficult to read, especially if you happen to enjoy picking up a book before you go to bed. This may be an attempt by a typesetter (someone who designs the inner pages of a book) to reduce the page count and therefore save money – however, it can affect the reading experience negatively.
On the other hand, it would look strange, and waste paper, if you were to publish a book with a large trim size when it only contained a few thousand words.
Common book trim sizes in the UK
The size of a book is called ‘trim size’ because books are printed on large sheets of paper, with x number of pages printed on a single piece of industry size paper and then trimmed to size by a machine.
Standard trim sizes are book measurements that are widely recognised across the industry. In the UK, these include A5 (148 x 210 mm), Royal (156 x 234 mm) and B-Format (198 x 129mm) books.
However, trim sizes have changed over the years. Popular sizes and formats have evolved over time, while self-publishing has also catalysed new trends, with authors and publishers experimenting with different book sizes.
In the UK and Europe, a book’s trim size is measured in millimetres but in the US, trim sizes are calculated in inches. That’s why when you’re publishing a book on Amazon KDP, for example, you’ll see values such as 7.8 x 5.1-inch books (one of the most common sizes for standard paperback books), while UK publishers might instead refer to a trim size of 210 x 148mm.
This post is primarily aimed towards authors who’re looking to have their book printed by a commercial (offset) printer, but if you’re publishing a book on Amazon, there’s another consideration to bear in mind.
Platforms such as Amazon KDP use standard trim sizes, so if want to publish something that falls outside of some of the most common trim sizes, you might find yourself struggling to publish a book on Amazon. If this is the case, choose the trim size that’s closest to the size you wanted.
Before you start to design your book, it’s worth checking to see if Amazon KDP can accommodate your preferred book size. You can view Amazon’s trim sizes and specific requirements for publishing on Amazon’s Kindle Direct Publishing help page.
Below is a list of the most common trim sizes in the UK, and we’ve included the measurements in inches, too, so you’ll be able to recognise them at a glance.
Pocketbook (175 x 108mm)
A compact size that’s portable and relatively cheap to produce, making it ideal for mass-produced books. For non-fiction, this trim size can make for a great gift book, for soft topics which are lighter on facts, containing shorter, pithy messages. Pocket-sized books can serve well as a companion guide alongside a main book.
Inches: 6.9 x 4.25
A-Format (178 x 110/111mm)
This is the smallest of the standard book sizes and is typically saved for mass-market paperbacks such as commercial fiction like romance, crime and thrillers – perfect for tucking into a suitcase for a holiday read.
Inches: 7 x 4.3
B-Format (198 x 129mm)
A popular trim size that’s slightly larger than the A-format book, B-format is the standard paperback size in the UK, especially for novels. This book size also works well for non-fiction books such as memoirs, self-help guides and workbooks that suit a trade paperback feel.
Inches: 7.8 x 5.1
A5 (210 x 148mm)
This is a good size for non-fiction titles. A5 is compact but still gives enough room for images and text that’s comfy to read. It’s cost-effective to print, easy to carry and feels approachable to readers, making it a popular trim size. If you’re writing a practical handbook, journal or short, non-fiction work under 50,000 words, A5 is a safe choice.
Inches: 8.3 x 5.8
Demy (216 x 138mm)
Slightly narrower and taller than an A5 book, Demy is often used for academic-style works and specialist non-fiction. Its size provides plenty of room for text-heavy works while giving a traditional publishing look, and it’s a common choice for trade paperbacks. If your book has a scholarly or professional tone, Demy might be the right fit.
Inches: 8.5 x 5.5
US Trade (229 x 152mm)
Although not a traditional UK size, US Trade is popular on self-publishing platforms like Amazon KDP and IngramSpark, with lots of international non-fiction books being printed at this size. Perfect for print-on-demand publishing, this format works well for business books, memoirs and titles aimed at an international audience. It allows for more words per page, which is helpful for longer manuscripts, but can feel a little large in the UK market compared to A5.
Inches: 9 x 6
Royal (234 x 156mm)
This is a popular trim size for non-fiction, including narrative non-fiction such as a memoir. It gives a professional, polished feel, making it ideal if you want your book to sit confidently alongside traditionally published titles.
Inches 9.2 x 6.1
A4 (297 x 210mm)
A4 is best suited for reference books but also works well if a book has lots of images and diagrams, or where layout is particularly important.
Inches: 11.7 x 8.3
What is a Trade Paperback?
A trade paperback describes a book that’s printed specifically for the book industry – such as booksellers and wholesalers – as opposed to paperbacks designed for mass production and sold in places such as airport shops.
In the UK, trade paperbacks are usually printed in sizes such as Royal, US Trade, and especially B-format. In fact, the term ‘trade paperback’ is often used synonymously for B-format books.
Trade paperbacks v mass-market paperbacks
A trade paperback is a cross between a mass-market paperback and a hardback book. It’s slightly larger, and its paper and binding are better in quality than a standard paperback, giving a professional appearance.
Mass-market paperbacks, on the other hand, are smaller (around 110 x 178 mm) and the paper is relatively cheap (and degrades faster). This format is used mainly for commercial fiction and often printed in large quantities.
Trade paperbacks were originally used by publishers to produce a less expensive version of a hardback book for sending to reviewers: a direct replica of the hardcover book without the hard casing. These days, they’re a highly popular format for non-fiction (and literary) titles, being more durable and providing a polished look.
Popular trim sizes for non-fiction books
Non-fiction books published in the UK generally suit the following trim sizes:
- A5 (210 x 148mm)
- Demy (216 x 138mm)
- US Trade (229 x 152mm)
- Royal (234 x 156mm)
- A4 (297 x 210mm)
How to pick a trim size
The best trim size for your book depends on lots of different factors, including your manuscript’s word count, who its potential readers will be, your budget, etc.
To help you make a decision, why not take a stroll around your local bookshop or library and check out some books in the same genre to see what similar books look like? (Or for speed, do it online – Amazon displays the dimensions of each book listed on the site under ‘Book details’, about half-way down the page.)
Make a note of the book’s trim size and compare a few to see what other authors are doing.
At a glance: what to consider when choosing a trim size
Printing costs
Your budget will influence what trim size you choose for your book. For instance, standard book sizes are much more cost-effective than a custom trim size that might require specialist printing equipment.
Distribution
Think about your market – where are your readers based? For example, popular trim sizes for a UK audience include A5 (148 x 210mm) or Royal (156 x 234mm), while US Trade (152 x 229mm) is often preferred amongst readers across the Pond.
Reader expectations & practicality
Consider how you want readers to use the book. For example, if you’ve written a journal or workbook, when you’re deciding on its trim size, keep in mind that it should be easy to carry or write in.
Paper
Your choice of paper can also influence the most suitable trim size for your book.
If you’ve chosen thicker paper, you’ll probably want a slightly larger trim size to prevent having a short, stocky book that looks too bulky. On the other hand, a larger trim would probably be unsuitable for thinner paper, making the book feel flimsy.
Note: the weight of paper (and its opacity) affects a book’s readability, durability and how any images inside it look.
Standard, mass-market paperbacks usually fall within the range of 70-90gsm (grams per square metre). This is considered to be quite thin and will exhibit some transparency. For more durable or premium books, the paper weight can range from around 140-170gsm.
Matching reader expectations while balancing printing costs and aesthetics will help your non-fiction book look professional and find its place in the market – and that’s why we’re here to help. Our team at Wellness Books will help you choose the best trim size, paper options and quality finish to match your audience and budget.
Ready to publish your book? We’re ready and waiting to help. Our talented designers are here to support you throughout the publishing process, and can advise you on the best format and design for your book.
For help, contact us at info@wellnessbooks.co.uk
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