DPI / Print Size Calculator

Two directions: 'I have a 3000×2000 image — how big can I print it at 300 DPI?' and 'I want a 10×8 inch print at 300 DPI — what pixel size do I need?' This tool handles both, with presets for the standard print resolutions (72 for web, 150 for draft, 300 for photo quality, 600 for fine art reproduction). Also shows megapixels, aspect ratio, and rough JPEG/PNG/RAW file size estimates so you can sanity-check storage and quality before sending to print.

DPI is not a property of an image file, which is the confusion underneath most of these questions. A file has a pixel count and nothing else; the DPI number stored in its metadata is a suggestion about physical size that only matters when something prints it. Changing that number in an editor without resampling does not add detail, it just relabels how large the same pixels should be drawn, which is why 300 DPI on its own tells you nothing about quality.

300 is a rule of thumb for things held in the hand, not a universal standard. The number comes from the resolving power of normal vision at reading distance, so it scales with how far away the print will be: a poster viewed from two metres looks sharp at 100, and a billboard is routinely produced at 15. Printing a large format at 300 wastes file size on detail no one will stand close enough to see.

The 72 preset is a historical artefact rather than a web resolution. It came from early Macintosh screens where one point equalled one pixel, and no modern display is 72 pixels per inch: a phone is often above 400. Web images are sized in pixels and the DPI field is ignored entirely, so exporting at 72 for the web changes nothing except the number in the header.

The file size estimates are approximations and JPEG is the reason. A photograph of a busy scene and a photograph of a clear sky at identical dimensions can differ several-fold after compression, because the format spends bytes on detail. Treat the figure as an order of magnitude for planning storage rather than a prediction of any particular file.