A5 is 148 by 210 mm, or 5.83 by 8.27 inches. It is the familiar European book size, and it is a legitimate self publishing trim at IngramSpark and Lulu.
Two things surprise people. Amazon KDP does not offer A5 in the US store, only through its Japanese storefront. And the paper standard everyone cites for it, ISO 216, explicitly says it does not apply to published books.
The Specification
| Millimetres | 148 x 210 |
| Inches | 5.83 x 8.27 |
| KDP printed value | 5.83" x 8.27" (14.8 x 21.0 cm) |
| KDP trim class | Regular |
| IngramSpark | 210 x 148, "(A5)" |
| Lulu name | A5 |
The measurement is confirmed identically by three independent platforms, so the dimensions are not in doubt. What is in doubt is the standard usually cited as their authority.
ISO 216 Does Not Cover Books
ISO 216:2007 is titled "Writing paper and certain classes of printed matter. Trimmed sizes. A and B series, and indication of machine direction". Its own scope statement is explicit:
"ISO 216:2007 specifies the trimmed sizes of writing paper and certain classes of printed matter... It does not necessarily apply to newspapers, published books, posters or other special items which may be the subject of separate International Standards."
So A5 as a book size is a convention borrowed from a paper standard, not a size that standard defines for books. That does not make it wrong, and printers offer it precisely because the convention is well established. It does mean that citing ISO 216 as the authority for an A5 novel is citing a standard that has disclaimed the application.
Availability, and the KDP Gap
- KDP paperback, US store: no. A5 appears only in the trim size table on Amazon's Japanese KDP site.
- KDP hardcover: no, at any storefront.
- IngramSpark paperback: yes.
- IngramSpark hardcover: case laminate only. No Digital Cloth, no jacketed.
- IngramSpark premium colour: no.
- Lulu: yes, listed as A5.
This is the most consequential finding on this page. If you are publishing through KDP from the US, UK or most other territories, A5 is simply not on the list, and choosing it means either using IngramSpark, using Lulu, or entering it as a custom trim.
KDP does accept custom paperback trims, with "Width must be within 4"-8.5" (10.16-21.59 cm). Height must be within 6"-11.69" (15.24-29.69 cm)." A5 falls inside both ranges, so it is reachable as a custom size even though it is not a listed one.
When A5 Makes Sense
Right for: books aimed primarily at European readers, where the proportions look native and 6 by 9 looks slightly American; books printed through European print on demand services, where A5 is the house size; and anything where you want a page taller and narrower in feel than the US sizes.
Wrong for: a US-first paperback, where you are fighting the platform for no gain; hardcover plans beyond case laminate; and premium colour interiors, which IngramSpark does not offer at this size.
A5 sits between 5.5 by 8.5 and 6 by 9 in area but is proportionally taller and narrower than either. That proportion is the actual reason to choose it, and it is a legitimate one.
What Deckle Does
A5 is one of Deckle's six trim sizes, listed as 148 by 210 mm and set internally as 5.8268 by 8.2677 inches, which is the exact millimetre conversion rather than a rounded approximation.
Deckle also offers BoD 135 by 215 mm, the pocket paperback format used by Books on Demand, the largest European self publishing print platform. If you are publishing into Europe, that size is worth comparing against A5, since it is narrower and slightly taller and is a real named preset rather than an improvised size.
Everything downstream follows the selection as usual: the text block resizes, the page count estimate updates, gutter enforcement recalculates, and the exported PDF carries bleed on three edges.
For the European print requirements that go with these sizes, see European print book requirements. For the alternatives, see book trim sizes explained and 6x9 book size.
Common Mistakes
- Assuming KDP offers A5. It is not a US listed size. Use custom trim, IngramSpark or Lulu.
- Citing ISO 216 as the authority for an A5 book. The standard's scope excludes published books.
- Planning a jacketed A5 hardcover. IngramSpark offers case laminate only at this size.
- Planning a premium colour A5 interior. Not offered at IngramSpark.
- Choosing A5 for a US-first release. You are working against every default for no benefit.
FAQ
Q: Can I publish an A5 paperback on KDP? A: Not as a listed size in the US store. It falls within KDP's custom trim range, so it can be entered manually.
Q: Is A5 the same as B format? A: No. B format is 198 by 129 mm, narrower and shorter, and is not a listed size at any major platform.
Q: What is the closest listed US size? A: 5.5 by 8.5 inches is 139.7 by 215.9 mm, slightly narrower and slightly taller, with full availability everywhere.
Q: Does ISO 216 define A5 for books? A: It defines the paper size. Its scope statement says it does not necessarily apply to published books.
Q: What is BoD 135 by 215? A: A European pocket paperback format offered by Books on Demand, and a separate preset in Deckle.