Guide 01
Choosing your trim size
Three standard sizes cover ninety-plus percent of novels. Here's how to pick the right one, and what it does to your page count and print cost.
Trim size is the physical dimensions of the printed book. It sounds like a small decision — it isn't. Your choice shapes page count, print cost per copy, shelf presence, and what a reader expects when they pick the book up. The good news: for novels, you probably want one of three standard sizes, and our generator defaults to them for a reason.
The three sizes that cover almost every novel
- 5 × 8" — compact, dense. Reads like a premium paperback. Higher page count for the same manuscript; more expensive per copy. Works for literary fiction, short novels, and anything where "feels like a real book" matters.
- 5.25 × 8" — the trade paperback default. What most indie novels ship as. Good balance of readability and cost. Safe default if you don't have a strong reason to pick otherwise.
- 6 × 9" — larger, airier. More words per page means lower page count and lower print cost. Standard for nonfiction and for sci-fi/fantasy novels that tend to be long. Readers perceive it as "substantial."
All three are supported directly by KDP Print and IngramSpark with no custom-size upcharge. All three also sit inside our default print CSS with KDP-compliant margins — the inside margin is wider than the outside so your text isn't swallowed by the spine.
The math you actually care about
KDP's Black & White print cost, US marketplace, 2026:
cost per copy = $0.85 fixed + $0.012 × page count
So a 300-page paperback costs you $4.45 per unit; a 450-page one costs $6.25. That's Amazon's print cost, not your royalty — price and royalty sit on top. Trim size affects page count directly because bigger pages hold more words.
Rough page-count estimates for an 80,000–110,000 word novel at our default typography:
| Trim | Words per page | 80k words | 110k words |
|---|---|---|---|
| 5 × 8 | ~260 | ~310 | ~425 |
| 5.25 × 8 | ~290 | ~280 | ~380 |
| 6 × 9 | ~330 | ~245 | ~335 |
These are approximations — actual numbers depend on theme, paragraph density, scene breaks, and how many chapter pages you have (each chapter opens on a fresh page, which costs you some efficiency). Use our Preview panel on /new to get real page counts for your specific manuscript.
How to decide
- Fiction, standard novel length, no strong preference → 5.25 × 8". It's what most indie novels are.
- Literary / short / premium → 5 × 8". Higher cost per copy but readers feel it.
- Sci-fi, fantasy, doorstopper, or anything over 120k words → 6 × 9". Lower page count keeps print cost sane and signals "substantial read" to the reader.
- Nonfiction, business, self-help, technical → 6 × 9" almost always.
You can generate the same manuscript at all three trims in one click on /new and compare the resulting PDFs. That's usually faster than reasoning about it in the abstract.
The short version
- Pick 5.25 × 8 unless you have a reason.
- Use the Preview panel to see the first two pages at the trim you're considering.
- Calculate
$0.85 + $0.012 × pagesfor your rough unit cost. - Price such that royalty covers unit cost plus the margin you want.
Anthony's take
TODO — revise with Spellbound specifics. This guide is v1: structure and numbers are correct for KDP 2026 pricing, but the "what it felt like when I actually held the printed proof" section is missing. Once Spellbound goes through KDP's proofing flow in all three trims, the real story — including the surprise moment at each trim — replaces this TODO.