Nothing leaves your device
The file is opened with the browser's own FileReader and drawn onto a canvas element inside this page. No copy is transmitted, stored or seen by anyone, which matters when the artwork is an unreleased cover.
Screens forgive a low-resolution picture and paper does not, so put anything you intend to print through this image DPI checker first. Drop the file in, tell it how big the picture will be on the page, and find out in a second whether it will hold up.
Choose a file, set the printed size in inches, and the resolution figures update straight away.
An image file has no physical size of its own. It has a pixel count, and nothing more. DPI only comes into existence at the moment you decide how large that picture will sit on the page, because it is simply the pixel count divided by the inches it has to cover.
That is why the same 1800 by 1200 photograph can be flawless and unusable on the same day. Placed three inches wide it delivers 600 pixels per inch and looks razor sharp. Stretched across a nine-inch spread it drops to 200, and every soft edge in it becomes obvious on paper.
Commercial presses lay down ink at a much finer grid than a monitor draws pixels, so they want roughly 300 pixels for every printed inch. Feed them less and the press faithfully reproduces exactly what you gave it, blur included. This tool works that arithmetic out for you, and does it locally: the picture is decoded by your own browser and never travels across the internet.
The file is opened with the browser's own FileReader and drawn onto a canvas element inside this page. No copy is transmitted, stored or seen by anyone, which matters when the artwork is an unreleased cover.
We report resolution across the width and down the height separately. If they disagree wildly, the image is being stretched out of proportion, and the smaller of the two figures is the one that decides how the print looks.
Resampling a small picture upward in Photoshop invents pixels by guessing at what sits between the real ones. The file grows, the reported DPI climbs, and the actual sharpness stays exactly where it started.
Photographs are forgiving because their edges are naturally soft. Diagrams, maps, signatures and hand-drawn illustrations show every stair-step, so aim for 600 to 1200 pixels per inch on anything built from crisp lines.
Our cover team looks at the source files and tells you honestly whether they can be salvaged or whether new artwork is the cheaper route.
Read the effective DPI the tool gives you against this scale before you commit a picture to an interior or a cover.
| Effective DPI | Verdict | What you will see on paper | What to do |
|---|---|---|---|
| 600+ | Excellent | Crisp enough for fine line art, maps and small type inside the image | Place it as is |
| 300-599 | Print ready | Matches what commercial presses and print-on-demand services ask for | Place it as is |
| 200-299 | Borderline | Photographs pass at a glance, fine detail and small text go mushy | Shrink the placement or source a bigger file |
| 150-199 | Poor | Visible softness, halos around edges, muddy shadow detail | Reduce the printed size or replace the image |
| Below 150 | Reject | Obvious pixel blocks and jagged diagonals, often flagged at preflight | Replace the image entirely |
| 72 | Screen only | A web-sized file placed at print size, the classic cause of a fuzzy cover | Go back to the original source file |
Three hundred pixels per printed inch is the number nearly every printer and print-on-demand service asks for, including Amazon KDP and IngramSpark. Line art, maps and anything with fine strokes benefit from 600 or higher, because sharp edges reveal every missing pixel.
No, and that is deliberate. Everything happens inside the page using the browser's FileReader and canvas features. Your artwork is never transmitted to us or to anyone else, so an unpublished cover stays private on your own machine.
Strictly speaking, PPI counts the pixels in a digital file while DPI counts the ink dots a press physically puts down. In everyday publishing conversation the two words are used interchangeably to mean the same thing, and printers who ask for 300 DPI artwork mean 300 pixels per printed inch.
You can change the number recorded in the file, but you cannot conjure detail that was never captured. Upscaling software guesses at the missing information, which softens edges rather than sharpening them. The honest fix is a larger original or a smaller placement on the page.
Not necessarily. The tag stored in a file is only metadata and says nothing about the pixel count, which is what actually matters. A photograph tagged 72 can still be five thousand pixels wide and print beautifully. Check the pixel dimensions, which is exactly what this tool reads.
Browsers can only decode the formats they natively support, so JPG, PNG, WebP and GIF work everywhere. For a PSD, TIFF or camera RAW, export a JPG copy first. The pixel dimensions carry over unchanged, so the reading you get is still accurate.
A monitor shows roughly a hundred pixels per inch, so it flatters low resolution files enormously. Ink laid on paper resolves three times finer, and every soft edge that the screen hid becomes plainly visible once the sheet is in your hand.
A full wraparound cover for a 6 by 9 book is roughly 12.5 inches wide once you add the spine and bleed, and 9.25 inches tall. At 300 pixels per inch that comes to about 3750 by 2775 pixels. Type your own figures into the tool and it will give you the exact target.
Send us your artwork at whatever resolution you have it, and we will rebuild the cover at the correct trim, bleed and spine, resolve any resolution problems, and hand back a file your printer accepts first time.
See Book Cover Formatting