Last reviewed by Robert Prime, 12 October 2026. Checked against Amazon’s own help pages: trim size, bleed and margins, paperback printing cost, paperback royalty and create a paperback cover.
Quick Answer: 8.5 x 8.5 inches (21.59 x 21.59 cm) is a square KDP paperback size. It is a “large” trim size, so it prints at the higher rate. Page limits: 24 to 590 (white), 24 to 550 (cream), 72 to 600 (standard colour), 24 to 590 (premium colour). Page size with bleed: 8.625 x 8.75 in. Spine width = pages x 0.002252 in (white) or x 0.0025 in (cream). Amazon.co.uk print cost: £2.15 for a black-ink book up to 110 pages. Hardcover is not offered at this size.
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Table of Contents
- Is 8.5 x 8.5 a KDP size?
- Page counts by paper and ink
- Interior page size, bleed and margins
- Spine width for an 8.5 x 8.5 book
- Full cover size
- What it costs to print on Amazon.co.uk
- Royalty: worked examples
- Who the square size suits
- Frequently asked questions
Is 8.5 x 8.5 a KDP size?
Yes, for paperbacks. Amazon’s trim size page lists “8.5” x 8.5" (21.59 x 21.59 cm)" in the paperback table. It does not appear in the hardcover table, so if you need a square hardback you will need a different printer or a different size.
People search for it three ways, and they all mean the same book: 8.5 x 8.5, 8.5x8.5 and 8.5 by 8.5. In metric it is 21.59 cm square, or 215.9 mm.
It is a large trim size. Amazon’s rule is that any book “more than 6.12 inches (155.5 mm) in width or more than 9 inches (228.6 mm) in height” is large. 8.5 inches wide is over 6.12, so you pay the large-trim printing rate (see the cost section below).
KDP also offers a slightly smaller square, 8.25 x 8.25 inches (20.96 cm), with higher page limits. Both are large trim sizes.
Page counts by paper and ink
From Amazon’s trim size table, 8.5 x 8.5 paperback:
| Ink and paper | Minimum pages | Maximum pages |
|---|---|---|
| Black ink, white paper | 24 | 590 |
| Black ink, cream paper | 24 | 550 |
| Black ink, groundwood paper | 24 | 578 |
| Standard colour ink, white paper | 72 | 600 |
| Premium colour ink, white paper | 24 | 590 |
The 72-page minimum for standard colour catches picture-book authors out. A 32-page picture book has to be premium colour at this size, or padded past 72 pages, which nobody wants.
Interior page size, bleed and margins
No bleed (text-only pages, nothing printed to the edge): set your page to 8.5 x 8.5 inches.
With bleed (pictures or colour running off the edge): KDP trims 0.125 in (3.2 mm) from the top, bottom and outside edge, so you add that to your page. The page size becomes 8.625 x 8.75 inches (21.91 x 22.23 cm): 0.125 in more on the width (one outside edge) and 0.25 in more on the height (top and bottom).
Minimum margins from the same Amazon page:
| Pages | Gutter | Outside, no bleed | Outside, bleed |
|---|---|---|---|
| 24 to 150 | 0.375 in | 0.25 in | 0.375 in |
| 151 to 300 | 0.5 in | 0.25 in | 0.375 in |
| 301 to 500 | 0.625 in | 0.25 in | 0.375 in |
| 501 to 700 | 0.75 in | 0.25 in | 0.375 in |
In millimetres: 0.25 in = 6.4 mm, 0.375 in = 9.6 mm, 0.5 in = 12.7 mm, 0.625 in = 15.9 mm, 0.75 in = 19.1 mm. “Gutter” is the inside margin, next to the spine.
Those are minimums, and minimums are where rejections happen. Page numbers and running heads count as printed content, and a margin set exactly on the line leaves no room for the small shifts in trimming. On a square page give yourself at least an extra eighth of an inch everywhere; the page is wide enough to afford it.
Spine width for an 8.5 x 8.5 book
Amazon’s cover page gives the spine as page count times a paper factor:
- White paper: pages x 0.002252 in (0.0572 mm)
- Cream paper: pages x 0.0025 in (0.0635 mm)
- Premium colour: pages x 0.002347 in (0.0596 mm)
- Standard colour: pages x 0.002252 in (0.0572 mm)
The spine depends on page count and paper only, so it is the same for every trim size. Here it is worked out for common 8.5 x 8.5 page counts:
| Pages | White | Cream | Premium colour |
|---|---|---|---|
| 24 | 0.054 in (1.37 mm) | 0.060 in (1.52 mm) | 0.056 in (1.43 mm) |
| 50 | 0.113 in (2.86 mm) | 0.125 in (3.17 mm) | 0.117 in (2.98 mm) |
| 100 | 0.225 in (5.72 mm) | 0.250 in (6.35 mm) | 0.235 in (5.96 mm) |
| 150 | 0.338 in (8.58 mm) | 0.375 in (9.52 mm) | 0.352 in (8.94 mm) |
| 200 | 0.450 in (11.44 mm) | 0.500 in (12.70 mm) | 0.469 in (11.92 mm) |
| 250 | 0.563 in (14.30 mm) | 0.625 in (15.88 mm) | 0.587 in (14.90 mm) |
| 300 | 0.676 in (17.16 mm) | 0.750 in (19.05 mm) | 0.704 in (17.88 mm) |
| 400 | 0.901 in (22.88 mm) | 1.000 in (25.40 mm) | 0.939 in (23.85 mm) |
| 500 | 1.126 in (28.60 mm) | 1.250 in (31.75 mm) | 1.173 in (29.81 mm) |
Standard colour uses the same factor as white paper, so read the White column. Cream paper is only available up to 550 pages at this size, and standard colour starts at 72 pages, so a few cells above are for reference only.
Spine text. Amazon says: “To include spine text, your book must have at least 79 pages.” If you build the cover in Cover Creator the minimum is 80. Under that, leave the spine blank or the cover is rejected. Keep spine text at least 0.0625 in (1.6 mm) from each edge of the spine.
For any other page count, the spine width calculator does the sum for you.
Full cover size
KDP wants one PDF: back cover, spine and front cover side by side, with 0.125 in of bleed on every outer edge. Amazon’s formula:
- Cover width = bleed + back cover width + spine width + front cover width + bleed
- Cover height = bleed + trim height + bleed
For 8.5 x 8.5 that is:
- Width = 0.125 + 8.5 + spine + 8.5 + 0.125 = 17.25 in + spine
- Height = 0.125 + 8.5 + 0.125 = 8.75 in
So a 100-page book on white paper has a cover of 17.475 x 8.75 inches, and a 200-page one on white paper 17.70 x 8.75 inches. Our KDP cover calculator gives the same numbers, and Amazon’s own cover calculator and template generator will draw the guides for you; use Amazon’s as the final check before upload.
What it costs to print on Amazon.co.uk
Amazon’s formula is: fixed cost + (page count x per-page cost) = printing cost. Bleed and cover finish do not change the price. These are the large-trim rates for books ordered on Amazon.co.uk, from the printing cost page:
| Ink | Pages | Fixed cost | Per page |
|---|---|---|---|
| Black ink, white or cream | 24 to 110 | £2.15 | none |
| Black ink, white or cream | 110 to 828 | £0.85 | £0.012 |
| Black ink, groundwood | 24 to 112 | £2.08 | none |
| Standard colour | 72 to 600 | £0.85 | £0.027 |
| Premium colour | 24 to 40 | £3.24 | none |
| Premium colour | 42 to 828 | £0.85 | £0.0598 |
Worked out for typical square books (our arithmetic from Amazon’s rates):
| Book | Printing cost on Amazon.co.uk |
|---|---|
| 32-page picture book, premium colour | £3.24 |
| 48-page picture book, premium colour | £3.72 |
| 100-page activity book, black ink | £2.15 |
| 100-page photo book, standard colour | £3.55 |
| 100-page photo book, premium colour | £6.83 |
| 200-page cookbook, black ink | £3.25 |
| 200-page cookbook, standard colour | £6.25 |
Colour is where the square format gets expensive. Premium colour costs five times as much per page as black ink at this size.
Royalty: worked examples
KDP pays 60% or 50% on paperbacks depending on list price. On Amazon.co.uk the rate is 60% for list prices of £7.99 and above and 50% at £7.98 and below (paperback royalty page). The sum is:
(royalty rate x list price) - printing cost = royalty
Using the costs above:
- 200-page black-ink book at £9.99: (0.60 x £9.99) - £3.25 = £2.74 a copy
- 32-page premium colour picture book at £12.99: (0.60 x £12.99) - £3.24 = £4.55 a copy
- 100-page premium colour book at £14.99: (0.60 x £14.99) - £6.83 = £2.16 a copy
Amazon adds VAT on top of the list price you set where it applies, and it calculates your royalty on the price without VAT (how UK taxes affect print list prices). Most UK books are zero-rated; see VAT on ebooks and print books for the exceptions, which include journals and planners. For other prices and page counts, try our KDP royalty calculator.
Who the square size suits
Square books open flat and wide, which suits:
- Picture books, where a spread is a 17-inch-wide canvas. Read how to format a picture book for KDP before you commit to a page count.
- Cookbooks and photo books, where a square image needs no cropping (cookbook formatting).
- Poetry, where short lines and white space are the point (poetry formatting).
- Activity and colouring books for children.
- Gift books, which are bought to be looked at.
It does not suit a novel. A text-only book at 8.5 inches wide gives line lengths far longer than readers like, and you pay the large-trim rate for no gain. For fiction, see the KDP trim size guide.
Frequently asked questions
Can I get an 8.5 x 8.5 hardcover on KDP?
No. Amazon’s trim size page lists 8.5 x 8.5 for paperbacks only. The hardcover table does not include it.
What is the page size with bleed for 8.5 x 8.5?
8.625 x 8.75 inches (21.91 x 22.23 cm). Add 0.125 in to the width and 0.25 in to the height.
How wide is the spine on a 100-page 8.5 x 8.5 book?
0.225 in (5.72 mm) on white paper, 0.250 in (6.35 mm) on cream, 0.235 in (5.96 mm) in premium colour.
What is the minimum page count?
24 pages, except standard colour, which starts at 72.
Is 8.5 x 8.5 the same as 21.59 cm square?
Yes. 8.5 inches is 21.59 cm, so 8.5 x 8.5 in is 21.59 x 21.59 cm (215.9 mm).
Why does my square book cost more to print than my 6 x 9 novel?
Because anything wider than 6.12 inches is a large trim size. For a black-ink book over 110 pages, Amazon.co.uk charges £0.012 a page for large trims against £0.010 for regular ones.
Can I put text on the spine of a 60-page book?
No. Amazon needs at least 79 pages for spine text (80 if you use Cover Creator).
Final thoughts
The square format is a good choice for books people look at rather than read straight through. Set your page to 8.625 x 8.75 inches if anything bleeds, keep your margins well above Amazon’s minimums, check the spine against the page count you actually upload, and price with the colour cost in mind.
When the file is ready, run it through the free KDP readiness check before you upload. It checks margins and bleed against KDP’s rules and shows you the problems before Amazon does.
— Robert publishing.co.uk
