A 5×8 book on KDP requires a minimum inside margin of 0.375”–0.875” depending on page count, 0.25” minimum outside margins, embedded fonts, and an even page count. The spine width is page count × 0.0025” (cream) or × 0.002252” (white). An 80,000-word novel at 5×8 produces roughly 310 pages, costing about $4.72 to print in B&W on cream paper. This is the mass-market paperback size — the standard for romance, thriller, and genre fiction.
Why 5×8
The 5” × 8” trim matches what genre fiction readers have been holding for decades. Mass-market paperbacks — the kind you pick up at the airport or grocery store — are 4.25” × 6.87”, but the closest KDP-supported size is 5” × 8”. It’s compact, portable, and signals “genre fiction” to readers before they read the cover copy.
Use 5×8 when your reader expects a book that fits in a purse or back pocket. If you’re writing romance, thriller, mystery, horror, or fast-paced genre fiction under 90,000 words, this is your trim.
Margin requirements for 5×8 on KDP
Minimum inside (gutter) margin
| Page Count | Minimum Inside Margin |
|---|---|
| 24–150 pages | 0.375” |
| 151–300 pages | 0.5” |
| 301–500 pages | 0.625” |
| 501–700 pages | 0.75” |
| 701–828 pages | 0.875” |
Minimum outside margins
| Edge | Minimum (no bleed) | Minimum (with bleed) |
|---|---|---|
| Outside | 0.25” | 0.375” |
| Top | 0.25” | 0.25” |
| Bottom | 0.25” | 0.25” |
Recommended professional margins
The smaller page means tighter margins feel more natural — but don’t push too close to the minimums.
| Edge | Recommended |
|---|---|
| Inside (gutter) | 0.65”–0.8” |
| Outside | 0.45”–0.6” |
| Top | 0.55”–0.7” |
| Bottom | 0.65”–0.8” |
At 5×8 with these margins, your text block is roughly 3.6”–3.9” wide — a comfortable line length for 10–11pt body text. Wider than that and you get too many words per line; narrower and the page feels cramped.
Use the KDP Book Calculator to see your page count and which margin tier applies.
Spine width
Cream paper: page count × 0.0025” White paper: page count × 0.002252”
| Pages | Cream Spine | White Spine |
|---|---|---|
| 200 | 0.500” | 0.450” |
| 250 | 0.625” | 0.563” |
| 300 | 0.750” | 0.676” |
| 310 | 0.775” | 0.698” |
| 350 | 0.875” | 0.788” |
| 400 | 1.000” | 0.901” |
At 5×8, your page count runs higher than larger trims (fewer words per page), so spines tend to be thicker. A 75K-word romance at 5×8 will have a 0.7”+ spine — plenty of room for title and author name. Calculate yours with the Spine Width Calculator.
Page count and printing cost
At 5×8 with 10–11pt body text, 1.3–1.45× line spacing, and professional margins:
| Word Count | Estimated Pages | Printing Cost (B&W, cream) |
|---|---|---|
| 40,000 | ~180 | ~$3.16 |
| 50,000 | ~220 | ~$3.64 |
| 60,000 | ~260 | ~$4.12 |
| 70,000 | ~290 | ~$4.48 |
| 75,000 | ~305 | ~$4.66 |
| 80,000 | ~310 | ~$4.72 |
| 90,000 | ~350 | ~$5.20 |
| 100,000 | ~390 | ~$5.68 |
Cost impact: 5×8 produces more pages than 5.5×8.5 for the same word count because fewer words fit per page. An 80K-word book is ~310 pages at 5×8 vs ~280 at 5.5×8.5 — about $0.50 more to print. For most genre fiction (60K-85K words), the cost difference is small enough to justify the right reader experience.
For books over 90K words, the page count at 5×8 gets expensive. Consider 5.5×8.5 or 5.25×8 if printing cost matters.
Enter your word count in the KDP Book Calculator for exact costs.
Cambric's romance and thriller templates are designed for 5×8 — the right margins, fonts, and scene breaks for genre fiction, ready to export to KDP.
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Cover dimensions
Cover width = 5” + spine + 5” + 0.25” (bleed) = 10.25” + spine Cover height = 8” + 0.25” (bleed) = 8.25”
Example: 310-page book on cream
- Spine: 310 × 0.0025” = 0.775”
- Cover width: 10.25” + 0.775” = 11.025”
- Cover height: 8.25”
- At 300 DPI: 3,308 × 2,475 pixels
Get exact dimensions with the Cover Size Calculator.
PDF export settings
- Page size: exactly 5” × 8” (360 × 576 points)
- Fonts: fully embedded
- Color: RGB, Grayscale, or CMYK
- Bleed: 0.125” on outside, top, and bottom if enabled
- Page count: must be even
- No printer marks
Typography at 5×8
The narrower page requires careful font sizing. Too large and you get 6-7 words per line (choppy reading); too small and it’s hard to read.
| Setting | Recommendation |
|---|---|
| Body font size | 10–11pt (10.5pt is the sweet spot) |
| Line spacing | 1.3–1.45× |
| Font choice | Garamond, Caslon, Bembo — compact, warm serifs |
| Words per line | 9–12 (ideal range for reading speed) |
Avoid Palatino or wider faces at 5×8 — they need more horizontal space than this trim provides. See font comparisons at this trim in the Book Fonts preview tool.
Best genres for 5×8
| Genre | Why 5×8 |
|---|---|
| Romance | Mass-market convention. Readers expect this size. |
| Thriller / suspense | Portable, fast-paced reading feel |
| Mystery / cozy mystery | Traditional genre paperback size |
| Horror | Compact, intimate feel matches the genre |
| Short novels (under 60K) | Fills more pages, feels substantial |
Not ideal for: nonfiction (too narrow for tables/figures — use 6×9), long literary fiction (use 5.5×8.5), anything over 100K words (page count and cost become prohibitive).
Related specifications
- 5×8 on IngramSpark — PDF/X-1a requirements
- 5.25×8 on KDP — slightly wider alternative
- 5.5×8.5 on KDP — the most popular fiction trim
- How to format a romance novel — genre-specific guide
- KDP Book Calculator — page count, spine, cost, royalty
- Spine Width Calculator — exact spine width