5.5 by 8.5 inches, or 139.7 by 215.9 mm, is a standard fiction size and the smallest trim with no availability gaps anywhere. It is the point at which KDP hardcover becomes available, and unlike 5 by 8 and 5.25 by 8 it qualifies for Expanded Distribution on every paper type.
IngramSpark labels it with its traditional British name, Demy octavo.
The Specification
| Inches | 5.5 x 8.5 |
| Millimetres | 139.7 x 215.9 |
| KDP printed value | 13.97 x 21.59 cm |
| KDP trim class | Regular |
| IngramSpark | 216 x 140, "Demy 8vo" |
| Lulu name | Digest |
Note IngramSpark's convention of printing height before width, which is the British ordering. The size is the same object described the other way round, a trap covered in book trim sizes explained.
Availability
Complete, which is the point of this size:
- KDP paperback: yes, all papers.
- KDP hardcover: yes, and this is the smallest size where KDP offers one.
- IngramSpark paperback: yes.
- IngramSpark hardcover: all three, case laminate, Digital Cloth and jacketed.
- IngramSpark premium colour: yes.
- KDP Expanded Distribution: yes, on all paper types, with no premium colour exception.
Only 5.5 by 8.5 and 6 by 9 have a clean sheet. The two smaller sizes both lose something.
The one restriction that still applies is not about size: KDP hardcovers are excluded from Expanded Distribution entirely, at every trim. If you want a hardcover in bookshops and libraries it has to come from IngramSpark.
Page Counts
KDP paperbacks run 24 to 828 pages on black ink and white paper and 24 to 776 on cream, with standard colour starting at 72. Hardcover is 75 to 550 across all papers, so a hardcover under 75 pages is not possible regardless of size.
IngramSpark sets limits by paper rather than size, reaching 18 to 1200 pages on 50lb white, with a minimum of 18 throughout. Details in KDP print file requirements and IngramSpark file creation requirements.
When to Choose It
Right for: novels of most lengths, memoir, general non-fiction, and any book where you want a slightly more compact object than 6 by 9 without giving up options. It is the safest choice if you are unsure, because nothing is closed off by picking it.
It is particularly well suited to a book in the 70,000 to 100,000 word range, where 6 by 9 would produce something a little thin and 5 by 8 something a little thick.
Less right for: very long novels, where the smaller page pushes the page count toward the platform ceiling, and heavily illustrated books, where 5.5 inches of width leaves a narrow text block once margins are subtracted.
One thing this size does well is spine. Because the page is smaller than 6 by 9, the same manuscript produces more pages and therefore a wider spine, and spine width is page count multiplied by paper thickness. KDP prints no spine text below 80 pages, so for a short book the smaller trim is what gets a title onto the spine at all.
What Deckle Does
5.5 by 8.5 is one of Deckle's six trim sizes, alongside 5 by 8, 6 by 9, 6.14 by 9.21, BoD 135 by 215 mm and A5.
Selecting it resizes the page for the print PDF, and the layout follows: the text block narrows, the estimated page count rises against 6 by 9, and Deckle's automatic gutter enforcement recalculates against the new page count band. The exported PDF carries bleed on three edges, so the file comes out at 5.625 by 8.75.
Deckle's default margins are tuned for 6 by 9, at 0.875 inch top, 1.25 inch bottom, 1.25 inch inside and 0.75 inch outside. At 5.5 by 8.5 those are still legal at both platforms but proportionally generous, so this is a size where reviewing the margins is worth the two minutes. See book margins and gutter explained.
Common Mistakes
- Assuming a KDP hardcover reaches bookshops. Hardcovers are excluded from Expanded Distribution at every size.
- Keeping 6 by 9 margins unchanged. They are proportionally large on a smaller page.
- Planning a hardcover under 75 pages. KDP's hardcover minimum applies regardless of trim.
- Reading IngramSpark's 216 x 140 as a different size. That is the same size in British height-first order.
- Choosing it for a heavily illustrated book. The usable measure is narrow.
FAQ
Q: Is 5.5 by 8.5 better than 6 by 9? A: Neither is better. This one is more compact and produces more pages; 6 by 9 is the market default. Both have full availability.
Q: What is Demy octavo? A: The traditional British name for this size, used by IngramSpark in its trim matrix.
Q: Can I get a hardcover at this size? A: Yes, at both KDP and IngramSpark, and it is the smallest size where KDP offers one.
Q: Does it qualify for Expanded Distribution? A: Yes, on every paper type, unlike 5 by 8 and 5.25 by 8 which lose it on premium colour.
Q: Which is the safest size if I am undecided? A: This one or 6 by 9. Both have no gaps in binding, paper or distribution.