Many text-led print interiors begin testing around 1.3× to 1.45× the type size, a relationship called leading in typography. That is a starting range, not a universal standard: x-height, line length, trim, audience, paper, and the face itself change what feels comfortable. Too tight can make a page feel congested; too loose can break paragraph continuity and expand the book unnecessarily.
Cambric shows that tradeoff across the complete manuscript. Change the book-wide leading, watch every page recompose, inspect dense and sparse chapters, and keep the approved setting connected to the print PDF and EPUB 3. Test line spacing in a real Cambric book project →
Line spacing by genre
| Genre | Recommended Spacing | Why |
|---|---|---|
| Literary fiction | 1.35–1.45× | Moderate, comfortable reading pace |
| Romance | 1.3–1.4× | Tighter = faster reading, matches pace |
| Thriller / suspense | 1.25–1.35× | Tight spacing creates urgency |
| Fantasy / sci-fi | 1.35–1.45× | Standard for long books |
| Horror | 1.3–1.4× | Tight, claustrophobic feel |
| YA fiction | 1.4–1.5× | More generous for younger readers |
| Middle grade | 1.45–1.55× | Even more open |
| Poetry | 1.0–1.2× within poems | Stanza spacing separate from line spacing |
| Nonfiction | 1.4–1.5× | Room for structural hierarchy |
| Self-help | 1.4–1.5× | Open, inviting feel |
| Large print | 1.4–1.5× | Comfort and accessibility |
Line spacing by trim size
| Trim | Spacing | Lines per Page |
|---|---|---|
| 5” × 8” | 1.25–1.35× | 30–34 |
| 5.25” × 8” | 1.3–1.4× | 31–35 |
| 5.5” × 8.5” | 1.35–1.45× | 32–36 |
| 6” × 9” | 1.4–1.5× | 33–38 |
Smaller trims need tighter spacing to fit enough text per page. Larger trims can afford to be more generous.
Page count impact
Line spacing is the second-biggest driver of page count after font size. For an 80,000-word novel at 5.5×8.5 in 11pt Garamond:
| Spacing | Lines/Page | Total Pages | KDP Cost |
|---|---|---|---|
| 1.2× (very tight) | 38 | ~235 | $3.94 |
| 1.3× (tight) | 35 | ~255 | $4.18 |
| 1.35× (standard) | 33 | ~280 | $4.72 |
| 1.4× (comfortable) | 32 | ~295 | $4.90 |
| 1.5× (generous) | 29 | ~325 | $5.26 |
| 2.0× (double) | 21 | ~460 | $6.88 |
Going from 1.35× to 1.5× adds ~45 pages and $0.54 per copy. Double-spacing (which is a manuscript format, not a book format) would add 180 pages and $2.16 per copy.
Before locking a spacing value, compare book formatting software on this point alone — a tool that can’t recompose your full page count as you adjust can’t show you this table for your own book.
1. Using Word’s default spacing
Word’s default line spacing is 1.15× with 8pt spacing after paragraphs — neither of which is appropriate for a book. Book interiors use:
- 1.3–1.45× line spacing (not 1.15×)
- First-line indent instead of space between paragraphs
- No extra space after paragraphs (except at scene breaks)
2. Double-spacing for the interior
Double-spacing is for manuscripts (submitted to agents/editors). Books are never double-spaced. If your book interior is double-spaced, it looks like a submission, not a published book.
3. Using space-between-paragraphs instead of first-line indent
This is a web/screen convention. Printed books use:
- ✅ First-line indent (0.25–0.35”) with no extra space between paragraphs
- ❌ No indent with extra space between paragraphs (this is for web pages and technical documents)
Exception: some modern nonfiction uses block paragraphs (no indent, space between). But fiction should always use first-line indents.
4. Inconsistent spacing throughout
If Chapter 1 has 1.35× spacing and Chapter 5 has 1.5× spacing, readers will feel something is wrong even if they can’t articulate what. Spacing must be identical throughout.
What “line spacing” actually means
| Term | Definition |
|---|---|
| Leading | The distance from one baseline to the next (typographic term) |
| Line spacing / line height | Same as leading, expressed as a multiplier (1.35× = 135%) |
| Single spacing | 1.0× — baseline to baseline equals the font size. Too tight for books. |
| 1.15× (Word default) | Slightly open. Still too tight for most books. |
| 1.3–1.45× (book standard) | The sweet spot for printed books. |
| Double spacing (2.0×) | Manuscript format only. Never for published books. |
Related guides
- Font size for books — the other big page count lever
- Best fonts for fiction — font recommendations
- Format a book for KDP — complete KDP guide
- KDP Book Calculator — page count and cost