Free Book Length Calculator (+ Guide)
A book length calculator that shows how long bestsellers in your genre are, from real books, and how your book compares.
by Navid Moazzez·Updated Sept 30, 2026·3 min read·Book length calculator
Pick your genre to see how long its bestsellers are, then compare your book and set your finish date.
Your genre
Your book
How long #1 bestsellers are
A bestseller's pages are the middle of its editions (hardcover, paperback, large print), from Open Library. Each sets a different number of words on a page, so compare pages at your own layout.
Recent #1 bestsellers in this genre
- Game On by Navessa Allen (2026): 384 pages
- Atmosphere by Taylor Jenkins Reid (2025): 352 pages
- Caught Up by Navessa Allen (2025): 370 pages
- Mate by Ali Hazelwood (2025): 368 pages
- Say You'll Remember Me by Abby Jimenez (2025): 352 pages
When you'll finish
Type your words above and your pace here to see your finish date.
What you type or upload stays in this browser. Page counts come from each font's own letter widths, and from line breaks measured on 24 public domain books.
Embed this tool on your site
Paste the code into any page: WordPress, Webflow, Squarespace, Ghost or plain HTML. It's free with the credit under it, which links back to navid.me.
This free book length calculator shows how long bestsellers in your genre are, and how your book compares.
It's built on real books: every New York Times #1 since 2010, and the Times' business and advice bestsellers. Page counts come from Open Library.
Here's how long books run in each genre, why pages don't turn neatly into words, and how to set your finish date.
TL;DRKey takeaways
What is a book length calculator?
A book length calculator tells you how long a book in your genre usually is, and how long yours will be.
Most use 1 table of word counts with no source. This one uses 854 bestsellers, and shows its sources.
How long are bestsellers in each genre?
Here's the page count of the middle book in each genre, and the range the middle half falls in:
- Middle book
- 512 pages
- Middle half
- 388 to 780
- Bestsellers
- 54
- Middle book
- 479 pages
- Middle half
- 380 to 824
- Bestsellers
- 17
- Middle book
- 418 pages
- Middle half
- 358 to 478
- Bestsellers
- 52
- Middle book
- 416 pages
- Middle half
- 385 to 465
- Bestsellers
- 223
- Middle book
- 414 pages
- Middle half
- 377 to 465
- Bestsellers
- 13
- Middle book
- 384 pages
- Middle half
- 352 to 485
- Bestsellers
- 41
- Middle book
- 360 pages
- Middle half
- 323 to 450
- Bestsellers
- 14
- Middle book
- 344 pages
- Middle half
- 280 to 460
- Bestsellers
- 124
- Middle book
- 340 pages
- Middle half
- 272 to 402
- Bestsellers
- 36
- Middle book
- 304 pages
- Middle half
- 251 to 352
- Bestsellers
- 125
- Middle book
- 272 pages
- Middle half
- 228 to 312
- Bestsellers
- 155
Fantasy runs longest: a quarter of its bestsellers pass 780 pages. Self-help runs shortest, and 3 in 4 of its bestsellers stay under 312 pages.
Why pages don't turn straight into words
Each page count is the middle of a book's editions: hardcover, paperback and large print. Each edition sets a different number of words on a page.
Your own layout changes it too. 80,000 words is 206 pages at 6" × 9" in EB Garamond at 11 pt, and 266 in Libre Baskerville.
So the calculator sets your book in pages at your layout, beside the bestsellers. The book page count calculator shows how each choice moves it.
How to set your finish date
A finish date comes from your pace, not a rule of thumb.
At 500 words a day, 5 days a week, 50,000 words takes 100 writing days: 140 days on the calendar. Type what you've written, and the calculator counts only what's left.
How to use the book length calculator
Your word count carries over to the other book tools.
Who is the book length calculator for?
It's for authors deciding how long their book should be:
- Words to pages calculator – writers turning words into pages
- Book outline generator – anyone planning the chapters to fill it
- Book page count calculator – authors planning the print edition
- Writing prompt generator – writers who need a way in
Every other tool is on my free tools page.
Book Length Calculator FAQs
Questions about book length? Here's what to know.
A book length calculator shows how long books in a genre usually are and how long yours will be.
This one uses New York Times bestsellers since 2010, with page counts from Open Library.
A book should be about as long as the bestsellers in its genre.
The middle New York Times bestseller runs 272 pages in self-help, 304 in business, 416 in thrillers and 512 in fantasy.
A self-help bestseller is 272 pages in the middle, and the middle half runs 228 to 312 pages, across 155 New York Times advice bestsellers since 2010.
A business bestseller is 304 pages in the middle, and the middle half runs 251 to 352 pages, across 125 New York Times business bestsellers since 2010.
A fantasy #1 bestseller is 512 pages in the middle, the longest middle book of any genre in the data, and a quarter of them pass 780 pages.
The time to write a book is the words left divided by your daily pace.
At 500 words a day, 5 days a week, 50,000 words takes 140 days, and the book length calculator works out your own date.
Yes, the book length calculator is free, with no sign-up.
The math runs on your device.
The book length calculator is for authors planning a book, who want to know how long it should be for its genre and when they'll finish it.
The words to pages calculator converts your word count, and the book page count calculator adds spine width and printing cost.
See all my free tools.
I did. I'm Navid Moazzez, and I made the book length calculator as one of my free tools on navid.me.
More about me.
Navid Moazzez
AI business strategist & AI OS builder
Navid Moazzez helps creators and founders master AI and build their own AI Operating System (AI OS) to automate their business and life.
Navid.me is reader-supported. When you buy through links on this site, I may earn an affiliate commission. Learn more about affiliate links.
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