5.25 by 8 inches, or 133.4 by 203.2 mm, sits between 5 by 8 and 5.5 by 8.5. It is a legitimate paperback size at both Amazon KDP and IngramSpark, and it is also the most restricted of the common novel sizes: paperback only at both platforms, no premium colour at IngramSpark, and absent from Lulu's list entirely.
If you are choosing it for a quarter inch of extra width, know what that quarter inch costs.
The Specification
| Inches | 5.25 x 8 |
| Millimetres | 133.4 x 203.2 |
| KDP printed value | 13.34 x 20.32 cm |
| KDP trim class | Regular |
| IngramSpark | 203 x 133 |
| Lulu | not offered |
What Is Not Available
This is the section that matters, because the restrictions are not obvious from any platform's size list:
- KDP paperback: yes.
- KDP hardcover: no. KDP hardcover begins at 5.5 by 8.5.
- IngramSpark paperback: yes.
- IngramSpark hardcover: none at all, not case laminate, not Digital Cloth, not jacketed.
- IngramSpark premium colour: no.
- KDP Expanded Distribution: yes, except on premium colour paper.
- Lulu: not offered.
That IngramSpark row is the significant one. At 5 by 8 IngramSpark offers all three hardcover bindings. At 5.25 by 8 it offers none. A quarter of an inch removes hardcover from both major platforms simultaneously, which no other common size does.
The practical rule: choose 5.25 by 8 only if you are certain the book will never have a hardcover edition. If a hardcover is possible later, 5 by 8 keeps IngramSpark open and 5.5 by 8.5 keeps both open.
Page Counts
At KDP the published bands match the other regular trim sizes: 24 to 828 pages on black ink and white paper, 24 to 776 on cream, 72 to 600 on standard colour. There is no hardcover row, because there is no hardcover.
At IngramSpark the limits are set by paper rather than size, up to 18 to 1200 pages on 50lb white. The full comparison is in IngramSpark vs KDP formatting requirements.
Is the Quarter Inch Worth It
Honestly, rarely. The size exists because printers can produce it, not because it solves a design problem the neighbouring sizes do not.
Against 5 by 8, you gain a slightly wider text block and lose IngramSpark hardcover. Against 5.5 by 8.5, you lose a quarter inch of width, an extra half inch of height, hardcover at both platforms and premium colour at IngramSpark.
The case for it is narrow: you want something marginally roomier than 5 by 8 for a paperback only edition, and the extra half inch of height at 5.5 by 8.5 would make the book look too tall for its width. That is a real aesthetic judgement, and if you have made it deliberately the size is fine. Choosing it because it appeared in a dropdown is not.
What Deckle Does
Deckle does not offer 5.25 by 8. The six available sizes are 5 by 8, 5.5 by 8.5, 6 by 9, 6.14 by 9.21, BoD 135 by 215 mm and A5 148 by 210 mm.
If you specifically need this size, the practical route is to lay the book out at 5 by 8, which is the nearest option, and accept the slightly narrower text block. Given that 5.25 by 8 closes off hardcover at both platforms, the substitution usually improves your position rather than costing you anything.
If the reason you wanted 5.25 by 8 was a wider measure, 5.5 by 8.5 is the better substitute and keeps every binding and paper option open.
For how the size decision propagates through the rest of the layout, see book trim sizes explained and book margins and gutter explained.
Common Mistakes
- Planning a hardcover. Neither platform prints one at this size.
- Planning a premium colour interior at IngramSpark. Not available here.
- Assuming Lulu can match it. Lulu does not list the size.
- Choosing it to split the difference. The neighbouring sizes have fewer restrictions in both directions.
- Committing before checking the paperback-only constraint. Changing trim size later reflows the whole book.
FAQ
Q: Can I get a 5.25 by 8 hardcover anywhere? A: Not at KDP or IngramSpark. IngramSpark's custom trim service may allow it, but it is not a listed size.
Q: Why does IngramSpark offer hardcover at 5 by 8 but not here? A: Binding lines are built around specific board sizes. There is no deeper reason and no way to argue it.
Q: Is it a standard size? A: It is a listed paperback size at the two largest platforms, so yes, but it is the most restricted of them.
Q: What should I use instead in Deckle? A: 5 by 8 if you want compact, 5.5 by 8.5 if you want room. Both keep more options open.
Q: Does the size affect Expanded Distribution? A: Only on premium colour paper, where it is not eligible. Black ink editions qualify.