Amazon KDP (Kindle Direct Publishing) is strict about image quality, and the requirements differ depending on whether you are uploading a Kindle eBook cover, a paperback cover or a manuscript. Getting held up over resolution, colour space or dimensions is frustrating when you are moments away from publishing. This is the complete checklist, with each of the three paths kept separate.
1. Three Different Files, Three Different Rule Sets
Most KDP confusion comes from treating "the cover" as one thing. It isn't. A Kindle eBook cover, a paperback cover and the images inside your manuscript are validated by separate pipelines with genuinely different requirements — including opposite advice on colour space.
| eBook cover | Paperback cover | Interior images | |
|---|---|---|---|
| File you upload | JPEG or TIFF | One PDF (back + spine + front) | PDF, DOC, DOCX, RTF, HTML or TXT |
| Colour space | RGB | CMYK recommended | Follows the manuscript |
| Size limit | Under 50 MB | 650 MB hard limit | 650 MB hard limit |
| Resolution | Pixel dimensions matter | 300 DPI at printed size | 300 DPI at printed size |
2. Kindle eBook Cover
This is the image shown on the Amazon product page and on the reader's device. It is a plain image file, not a PDF.
| Requirement | Spec |
|---|---|
| File format | JPEG (.jpeg/.jpg) or TIFF (.tif/.tiff) |
| Colour space | RGB |
| Maximum file size | Must be less than 50 MB |
| Minimum dimensions | 1,000 px height × 625 px width |
| Ideal dimensions | 2,560 px height × 1,600 px width |
| Maximum dimensions | 10,000 px on either side |
| Aspect ratio | Height:width of at least 1.6:1 |
3. Paperback Cover
This one surprises people: the paperback cover is not a JPEG. KDP requires "a single PDF file that includes the back cover, spine, and front cover as one image."
| Requirement | Spec |
|---|---|
| File format | A single PDF (back + spine + front combined) |
| Colour space | CMYK recommended for print accuracy |
| Maximum file size | Files over 650 MB will not convert; 40 MB or less recommended |
| Image resolution | Images placed at a minimum of 300 DPI |
| Bleed | Add 0.125" (3.2 mm) to the top, bottom and outside edges |
Calculating Print Cover Dimensions
Full cover width is back cover + spine + front cover, and the spine grows with your page count and paper type. Rather than reproduce a formula that changes with paper stock, use KDP's own Cover Calculator — enter trim size, page count and paper type and it returns the exact dimensions plus a template.
What you do need to remember is the bleed. It is 0.125 inch (3.2 mm) per bleeding edge, not a quarter inch. For a 6×9 paperback that means the cover artwork extends 0.125" past the trim on the top, bottom and outside edges — so height becomes 9 + 0.125 + 0.125 = 9.25 inches, which at 300 DPI is 2,775 pixels tall.
4. Interior Images
Images inside the manuscript — photos, illustrations, diagrams — are judged at the size they are printed, not as standalone files.
| Requirement | Spec |
|---|---|
| Manuscript format | PDF, DOC, DOCX, RTF, HTML or TXT — PDF is required if anything bleeds |
| Image resolution | At least 300 DPI at printed size |
| Practical ceiling | Around 600 DPI, to keep the file under the size limit |
| Maximum file size | 650 MB |
| Bleed | Extend images 0.125" (3.2 mm) past trim on top, bottom and outer edges |
With bleed, the PDF page itself is set up 0.25" (6.4 mm) taller and 0.125" (3.2 mm) wider than your trim size — taller by two bleeds because both top and bottom bleed, wider by only one because the inner edge is bound.
5. How KDP Actually Judges Resolution
This is the part that matters most, and the part most guides get wrong. KDP does not read the DPI number stored in your file's metadata. It works out the effective resolution from the pixels you supplied and the size the image is printed at. In KDP's own words:
Divide the number of pixels by the image size. For example, the pixel count of your image is 1200 x 1800, and the image is 4" x 6". That means your image has 300 DPI.
So a 1200 × 1800 px image is 300 DPI when placed at 4×6 inches, and 150 DPI when the same file is stretched across 8×12 inches. Nothing about the file changed — only the printed size did.
6. Common KDP Errors
Here are the most common problems and how to fix them:
"Image resolution is too low"
Your image does not carry enough pixels for the size it is printed at. Work out what you need: printed width in inches × 300 = minimum pixel width. A photo running the full width of a 6-inch page needs at least 1,800 px across.
If the pixels are there but the image is landing on the page far too big, the DPI tag is the likely culprit — our KDP Image Tool rewrites it to 300 so the image places at its real size. If the pixel count genuinely falls short, no tool can rescue it; the image has to be recreated or reproduced smaller.
Colour space mismatches
The right answer depends on the file. A Kindle eBook cover must be RGB. A paperback cover should be CMYK, because that is what the press prints in. Mixing colour spaces within one file "can cause color variance and unexpected results," so pick one per file and stay with it.
"Cover dimensions don't meet requirements"
Download KDP's official cover template from the Cover Calculator for your exact trim size, page count and paper type, and design to those precise dimensions.
"File format not supported"
Check which file you are uploading. A paperback cover must be a PDF — a JPEG will be refused. A Kindle eBook cover must be JPEG or TIFF. Manuscripts accept PDF, DOC, DOCX, RTF, HTML or TXT, and must be PDF if anything bleeds.
7. Pre-Submission Checklist
Before submitting to KDP, verify:
- ✓ Pixel dimensions are sufficient for the printed size at 300 DPI (printed inches × 300)
- ✓ The DPI tag reads 300, so images place at their true size in your layout program (check it here)
- ✓ Colour space matches the file: RGB for a Kindle cover, CMYK for a paperback cover
- ✓ The right container: PDF for a paperback cover, JPEG or TIFF for an eBook cover
- ✓ File size is within limits — under 50 MB for an eBook cover, under 650 MB for print files
- ✓ Bleed of 0.125" is included on every bleeding edge if your design runs to the trim
- ✓ Text is legible at thumbnail size (for the cover)
6. Tools We Recommend
| Task | Free Tool |
|---|---|
| Fix DPI metadata | ConvertImageDPI KDP Tool |
| Check current DPI | ConvertImageDPI Checker |
| Design book cover | Canva, Affinity Publisher (free trial) |
| Convert between RGB and CMYK | Photopea (free, online) |
| Exact cover size and template | KDP Cover Calculator |
Frequently Asked Questions
What is the difference between an eBook cover, a paperback cover and interior images?
They are three separate uploads with three different rule sets. A Kindle eBook cover is a JPEG or TIFF in RGB, under 50 MB. A paperback cover is a single PDF containing back, spine and front, and should be CMYK. Interior images live inside your manuscript and are judged at the size they are printed.
Does changing the DPI tag improve image quality?
No. The tag is metadata; it does not add or remove a single pixel. What it changes is the physical size the image is given when you place it in a layout program, and that in turn changes the effective resolution KDP calculates.
My camera saves photos at 72 DPI. Is that a problem for KDP?
Only indirectly. Cameras write 72 because of an old screen convention, and the number says nothing about how much detail the photo holds. It becomes a problem when Word or InDesign uses that 72 to place the photo roughly four times too large, dropping the effective resolution well under 300.
KDP still reports low resolution after I set 300 DPI. What now?
That means the pixels genuinely are not there. Multiply the printed width in inches by 300 to get the pixel width you need: an image running the full 6 inches of a 6 by 9 page needs at least 1,800 pixels across. If your file falls short, reproduce it smaller on the page or recreate it at a higher resolution.
How many pixels do I need for a full-page image in a 6 by 9 paperback?
Without bleed, 6 by 300 = 1,800 pixels wide and 9 by 300 = 2,700 pixels tall. With bleed the page grows by 0.125 inch on each bleeding edge, so a full-bleed image needs about 1,838 by 2,775 pixels.
Should my files be RGB or CMYK?
It depends on the file. A Kindle eBook cover must be RGB. A paperback cover should be CMYK, because that is what the press prints in. Mixing colour spaces inside one file can cause colour variance, so pick one per file and stay with it.