5″ × 8″ Trim Size Guide
The mass-market paperback. Compact, familiar, and built for genre fiction that readers devour in a single sitting.
What is the 5″ × 8″ trim size?
The 5″ × 8″ trim is the classic mass-market paperback format. If you have ever picked up a romance, thriller, mystery, or horror novel from a drugstore spinner rack or airport bookshelf, you have held this size. It is compact, lightweight, and designed for one-handed reading.
For indie authors, 5″ × 8″ signals genre fiction. Readers in romance, thriller, mystery, and horror expect this format. It fits in a coat pocket, weighs less than larger trims, and printing costs are moderate for books under 400 pages. The tradeoff is tighter margins and less room for typography to breathe, which means your font choice and margin setup matter more at this size than at any other.
Both Amazon KDP and IngramSpark support 5″ × 8″ as a standard trim size with no custom-size surcharges. It is available in both cream and white paper stocks.
Margins & requirements
KDP and IngramSpark enforce minimum margins. Meeting them is not enough — professional interiors need breathing room beyond the minimums.
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″ |
Recommended margins for professional interiors
| Margin | Recommended Range |
|---|---|
| Inside (gutter) | 0.7″ – 0.8″ |
| Outside | 0.5″ – 0.55″ |
| Top | 0.6″ – 0.7″ |
| Bottom | 0.7″ – 0.8″ |
These values give your text block enough breathing room to look traditionally published while keeping page count reasonable. Use our KDP Book Calculator to see how different margin choices affect your page count and printing cost.
Word count to page count
Estimates based on 11pt body text, 1.4× leading, and recommended margins. Your actual count will vary with font, paragraph spacing, and chapter break style.
| Word Count | Estimated Pages |
|---|---|
| 50,000 | ~215 |
| 60,000 | ~255 |
| 70,000 | ~295 |
| 80,000 | ~340 |
| 90,000 | ~380 |
| 100,000 | ~420 |
For a precise estimate with your exact word count, try the KDP Book Calculator. It factors in your trim size, font size, and margins to give you an exact page count and printing cost.
Spine width calculation
Your cover template requires an exact spine width. The formula depends on your paper stock:
| Paper Stock | Formula | Example (300 pages) |
|---|---|---|
| Cream / off-white | page count × 0.0025″ | 0.75″ |
| White | page count × 0.002252″ | 0.676″ |
Font & layout recommendations
The 5″ × 8″ trim has a narrow text block, so your typography choices need to work within tight horizontal space. Here is what works well:
Body text size
10.5 – 11pt. Anything smaller strains the eye; anything larger eats through pages and inflates printing costs. 11pt is the sweet spot for most fiction at this trim.
Line spacing (leading)
1.3 – 1.5× the body size. At 11pt, that means 14.3 – 16.5pt leading. Tighter leading (1.3×) reduces page count; looser leading (1.5×) improves readability. For genre fiction, 1.4× is a strong default.
Recommended fonts
Garamond, Caslon, Baskerville. These are the workhorses of book typography — designed for sustained reading at small sizes. They set efficiently (more words per line than wider faces) and look correct to readers who have spent years with traditionally published paperbacks. Browse options with our book font finder.
Paragraph style
First-line indent, no space between paragraphs. This is the standard for fiction. Use a 0.25″ – 0.35″ indent. Block paragraphs (space between, no indent) waste vertical space at this trim size and are better suited to nonfiction at 6″ × 9″.
Who should use 5″ × 8″
This trim size works best for books that readers consume quickly and in volume. The compact format is part of the reading experience — it signals a fast, immersive read.
Romance
The core audience for 5″ × 8″. Romance readers buy in volume, expect the mass-market feel, and want a book that fits in a purse. If you are formatting a romance novel for print, this is the default choice.
Thriller & Mystery
Fast-paced stories benefit from the compact format. Thrillers and mysteries at this size match what readers see from major publishers. The page count for a typical 70,000–90,000 word thriller (295–380 pages) sits in the sweet spot for printing costs.
Horror
Horror paperbacks have been printed at this size since the 1970s. The format carries genre expectations. A slim horror novel (50,000–70,000 words) produces a 215–295 page book that feels right in readers' hands.
Genre fiction (general)
Westerns, action-adventure, military fiction, and other genre categories all work well at 5″ × 8″. If your book would have been a mass-market paperback at a traditional publisher, this is the right trim. For literary fiction or cross-genre works, consider 5.5″ × 8.5″ instead.
Frequently asked
Is 5″ × 8″ a good size for romance novels?
How many pages is 80,000 words in a 5″ × 8″ book?
What margins do I need for a 5″ × 8″ book on KDP?
What is the difference between 5″ × 8″ and 5.5″ × 8.5″?
Can I use 5″ × 8″ on IngramSpark?
Ready to format your 5″ × 8″ book?
Cambric applies the correct margins, fonts, and page layout for 5″ × 8″ automatically. Pick a template, import your manuscript, and export a print-ready PDF. Read our guide on formatting a book for KDP to get started.