The honest short answer: between 5,000 and 100,000 words, and the range is that wide because “ebook” describes a file format rather than a kind of book. A giveaway guide and a fantasy novel are both ebooks and have almost nothing in common.
So the useful question is not how long an ebook should be. It is what job this particular book has to do, because that decides the length, and the length then decides almost everything else — how long it takes to write, what you can charge, and whether anybody finishes it.
The numbers, by type of book
| Kind of book | Words | Chapters | Reading time |
|---|---|---|---|
| Lead magnet / giveaway guide | 5,000 – 8,000 | 5 – 7 | 30 – 45 min |
| Short how-to or “quick start” | 10,000 – 15,000 | 8 – 12 | 1 – 1.5 hrs |
| Full non-fiction guide | 25,000 – 40,000 | 10 – 14 | 2 – 3 hrs |
| Course companion / workbook | 12,000 – 20,000 | 10 – 15 | Worked through, not read |
| Research report | 12,000 – 18,000 | 8 – 12 | 1 – 2 hrs |
| Novel | 60,000 – 90,000 | 20 – 35 | 5 – 8 hrs |
Why shorter usually wins
The instinct is that a longer book is a more serious book, and therefore worth more. In self-publishing this is mostly backwards, for three reasons that all point the same way.
Finishing rate. A book somebody finishes is a book that gets reviewed, recommended, and followed by a purchase of your next one. A 40,000-word book that gets abandoned at chapter three has done less for you than a 7,000-word one that got read on a train.
Cost of printing. If you ever put the book out as a print-on-demand paperback, page count is subtracted from your royalty directly. A long book at a modest price can pay you almost nothing.
Padding is visible. Length that was added to hit a number reads as length that was added to hit a number. The third worked example, the history-of-the-subject chapter, the recap chapter at the end — readers can feel all of it, and it is what one-star reviews are made of.
Write the shortest book that completely solves the problem you promised to solve. Then stop.
When longer genuinely is right
- Fiction. Readers of most genres expect a novel to be a novel. Under about 50,000 words you are writing a novella, which is a legitimate form with a smaller market and different expectations.
- Reference. A book somebody keeps on a shelf and dips into is allowed to be long, because nobody is trying to finish it in one sitting.
- Authority non-fiction. If the book exists to establish that you are the person who knows this subject, thin is a problem. But depth is what gets you there, not word count.
Chapter length matters more than book length
A reader does not experience 30,000 words. They experience one chapter at a time, usually in the gaps of a day. Chapters of 1,000 to 1,800 words are what makes a book feel readable — long enough to say something, short enough to finish before the bus arrives.
This is also the single most reliable structural fix for a book that feels heavy. Take the 4,000-word chapter and make it three. Nothing was cut, and the book got easier.
How to decide, in one minute
- 1Name the job. Is this book collecting email addresses, selling for $9.99, or establishing that you know a subject? Each has a different right length.
- 2Name the reader’s deadline. How long do they realistically have? A giveaway guide is read in one sitting or never.
- 3Pick from the table above, then subtract 20%. Almost every first draft is longer than it needed to be.
- 4Divide by 1,400 to get a chapter count. That is your outline’s shape before you have written a word.
Work out the page count and reading time for a target word count.
Word count plannerHow BookArc handles length
You pick the format first — lead magnet, how-to guide, course, novel, report or workbook — and each one plans within its own chapter range at its own default length, because a course module and a novel chapter are not the same object. The chapter plan then arrives before anything is written, with a words-per-chapter dial on it, so the length is a decision you make while looking at the actual chapter list rather than a guess made in advance.