How to Get KDP Cover Dimensions Right (Without Losing Your Mind)

Paperback spines, 0.125" bleed, 300 DPI — the exact math, with worked examples.

The single most common reason a KDP cover gets rejected is a wrong size. The listing looks fine in preview, then the upload errors out and you're Googling "why is my cover rejected" at midnight.

Here's the exact math for every format, plus the mistakes that trip everyone up. If you just want the answer, the free cover calculator does all of this for you — this post is for understanding why.

1. Kindle ebook covers: the easy one

Amazon's ideal Kindle cover is 1600 × 2560 pixels, a 1.6:1 height-to-width ratio.

• Minimum is 1000 pixels on the longest side — anything below gets a low-quality flag.
• JPG or TIFF, RGB, under 50 MB.
• Kindle covers are front-only. There's no spine, no back, and no bleed — bleed only matters for print. (A surprisingly common question.)

So for a Kindle ebook, just make the art 1600 × 2560 px and you're done.

2. Paperback covers: where everyone gets stuck

The paperback cover you upload is not the front page. It's a full wrap — back cover + spine + front cover — flattened into one image.

The full-wrap size is:

Width  = (trim width × 2) + spine width + (bleed × 2)
Height = trim height + (bleed × 2)

The bleed

KDP prints on a bigger sheet and trims down to the final size. The 0.125" you add on every edge is the bleed — the part that gets cut off. Your background art must extend into the bleed, or you'll get white edges after trimming.

The spine: the formula nobody remembers

Spine width comes from the book's page count and paper type:

Spine = page count × paper thickness

• White paper: 0.002252 inches per page
• Cream paper: 0.0025 inches per page

Worked example: 6" × 9", 250 pages, white paper

Trim:            6" × 9"
Bleed:           0.125"
Spine:           250 × 0.002252" = 0.563"

Full width:      (6 × 2) + 0.563 + (0.125 × 2) = 12.813"
Full height:     9 + (0.125 × 2) = 9.25"

At 300 DPI:      12.813 × 300 = 3844 px
                 9.25 × 300   = 2775 px

So the flattened cover file is 12.813" × 9.25", or 3844 × 2775 px at 300 DPI — the same numbers the cover calculator spits out.

3. Hardcover: mostly the same, plus two gotchas

Hardcover uses the same full-wrap math (front + spine + back, same bleed and DPI), with two extra rules:

• 0.625" safe margin from the trim edge (vs 0.5" for paperback) — the case wrap moves more.
• A 0.4" hinge zone along the inner edges where the board hinges; keep critical art out of it.

4. Common trim sizes (so you know what to pick)

For low-content books (journals, planners, notebooks) the 8.5" × 11" and 6" × 9" sizes dominate.

5. The 4 mistakes that get covers rejected

1. No bleed / art doesn't extend into bleed — white edges after trim. The #1 cause.
2. Wrong DPI — KDP wants 300 DPI at native resolution. A 150 DPI image upscaled to 300 still gets flagged.
3. Square or off-ratio Kindle cover — use 1600 × 2560, not 1:1.
4. Guessing the spine width — using a generic "0.5 inch spine" for a 400-page book. The spine grows with page count; never guess.

6. The shortcut

You don't need to remember any of this — I built a free KDP cover calculator that does it in one click:

• Kindle: exact 1600 × 2560 px
• Paperback & hardcover: full-wrap inches + pixels at 300 DPI, with spine width from your page count and paper type
• No signup, runs entirely in your browser, nothing uploaded

Always confirm the final file against KDP's own official cover calculator (in your KDP dashboard) before you pay for a print proof — the numbers should match.

More free KDP tools: Royalty Calculator · ISBN Converter · Description Formatter · Keyword Checker · Keyword Generator · Launch Kit Generator

Cover rejected and you don't know why? Tell me the error in the comments — I'll point you at the fix.