DPI / print size
Pixels ↔ inches/cm at a given DPI.
This runs in your browser. Nothing is uploaded.
About DPI / print size
Works out how large an image prints at any DPI you pick, showing the physical size in inches and centimetres from its pixel dimensions, calculated live in your browser.
The print shop says 300 DPI and the photo says 4032 by 3024, and connecting those two facts is the whole problem. It comes up every time somebody asks whether a phone photo will fill an A4 page, whether a logo pulled off a website is big enough for a banner, or why a file that looked sharp on screen printed like a fax.
Load an image and it reads the pixel dimensions, then divides them by the DPI value on the slider. The print size updates as you drag, in inches and centimetres, with no button to press and no file produced. Nothing is modified or downloaded — this is a calculator that happens to take an image as its input rather than asking you to type the numbers.
What it cannot tell you is whether your image “is” 300 DPI, because no image is. DPI is a decision made at print time about how densely to lay the pixels down, not a property of the pixels themselves. Some files store a resolution tag, and this ignores it deliberately; the tag is a suggestion that any print dialogue can override. Pixel count is the only fact here.
How to use DPI / print size
- 1Drop an image onto the panel to read its pixel dimensions.
- 2Drag the DPI slider to the density your printer or print shop expects.
- 3Read the print size in inches and centimetres below.
What it won't do
- A read-only calculator; it does not resize or resample anything.
- Ignores any DPI or resolution tag stored inside the file.
- Assumes the whole image is printed, with no allowance for bleed or margins.
Common questions
How many pixels do I need for a 300 DPI print?
Multiply the printed size in inches by 300. A 4 by 6 inch photo needs 1200 by 1800 pixels, a 5 by 7 needs 1500 by 2100, and A4 at 300 DPI works out to roughly 2480 by 3508. Anything above those numbers is headroom for cropping; anything below means the printer is interpolating.
Is my image 300 DPI?
The question does not quite have an answer, because DPI is not stored in the pixels. Any image can be printed at any DPI — a 3000-pixel-wide photo is 300 DPI across 10 inches and 150 DPI across 20. What you actually have is a pixel count, and the DPI follows from how big you choose to print it.
Does this change my image's DPI metadata?
No. Nothing is written, altered or downloaded; the tool only reads the dimensions and does the arithmetic. If the calculation tells you the print is too small, the only real fixes are to print it smaller or to start from a higher-resolution original. Resampling upward adds pixels without adding detail.
What DPI do I actually need?
Around 300 for anything held at reading distance, such as photo prints, books and business cards. Posters viewed from a metre or two are fine at 150, and large-format banners are routinely printed at 100 or less because nobody stands close enough to notice. Higher DPI on a banner buys you a huge file and nothing visible.
Related tools
Why this one doesn't upload your file
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