What this tool does
An image on a screen is a grid of pixels. When you print it, those pixels are spread across a certain number of inches, and the number of pixels per inch is the effective resolution, usually called DPI. If there are too few pixels for the size, the printer has to stretch them, and the result looks soft or blocky. This tool reads the pixel size of your image, compares it with the print size you choose, and tells you the effective DPI.
How to use it
- Pick the size the image will print at. For a full-page picture in a paperback, use the trim size of the book and turn on bleed if the artwork runs off the edge.
- Choose your image. Only its width and height in pixels are read.
- Read the verdict. If the result is marginal or low, the message tells you how many pixels you need.
The 300 DPI rule
For print, 300 pixels per inch is the standard target and the number print-on-demand services ask for. At 300 DPI and above, the picture looks sharp to the eye at reading distance. Between 200 and 300 it usually prints acceptably but may look a little soft on close inspection, especially line art, where edges are the whole point. Below 200, the loss of sharpness is usually obvious. Line art suffers more than photographs, because a photo hides softness in its texture while a hard black line shows every blurry pixel.
How many pixels you need
Multiply the print size in inches by 300. A full page on an 8.5 × 11 inch book needs 2550 × 3300 pixels without bleed. With bleed, the print area is 8.625 × 11.25 inches, which needs 2588 × 3375 pixels. A 6 × 9 inch page needs 1800 × 2700 pixels, or 1838 × 2775 with bleed. The tool shows the exact numbers for whatever size you pick.
Bleed in the interior
If artwork touches the edge of the page, KDP wants it to extend 0.125 inches past the trim on the outside edge, and 0.125 inches at the top and bottom. That is why a bleed page is 0.125 inches wider and 0.25 inches taller than the trim size. Check the box above when your image fills the page edge to edge, and leave it off when your art sits inside the margins.
The DPI number saved inside a file does not matter
Many image files carry a DPI tag such as 72 or 300. It is only a label. What decides print quality is the actual number of pixels compared with the physical size on the page. A 1000-pixel-wide picture marked 300 DPI is still only 3.3 inches wide at true 300 DPI, and a 3000-pixel picture marked 72 DPI prints perfectly well at 10 inches. That is why this tool ignores the tag and looks at pixels only.
Why upscaling does not fix a low result
Enlarging a small image in an editor makes the file bigger, but it cannot create detail that was never captured. The pixels are only guessed from the neighbors, and the picture usually looks smoother and blurrier. The fix is to start from a larger original or to redraw it at a bigger size. If you generate artwork with an AI tool, check what resolution it outputs before you commit to a page layout.
Shape matters too
If the proportions of the image do not match the print area, it must be cropped or stretched to fit. The tool warns you when the shapes differ by more than about 1%, because a picture that looks fine in the preview can lose its edges, or distort, when it is placed on the page.
Frequently asked questions
Does my image get uploaded?
No. Your browser reads the width and height of the file on your device. Nothing is sent anywhere.
What DPI should I aim for?
300 effective DPI at the size the image will print. Line art especially benefits from it.
My image says 72 DPI in my editor. Is that bad?
Not by itself. The label does not matter. Only the pixel width and height compared with the print size count.
Can I make a low-resolution image sharper?
Not really. Enlarging adds pixels but not detail. Start from a larger original if you can.
Do I need bleed?
Only if the artwork runs to the edge of the page. Art that stays inside the margins does not need it.