DPI / PPI & Print Size Calculator
Turn pixels into a print size, or a print size into the pixels you need, at any DPI — in inches and centimetres.
Pixels, inches, and resolution
A digital image has no physical size until you decide how many pixels to pack into each inch of paper. That choice — the DPI — is the bridge between the two worlds: more pixels per inch means a smaller, sharper print; fewer means a larger, softer one from the same file.
Planning around a fixed pixel count? The Megapixels & Resolutioncalculator relates dimensions to a camera’s megapixels, and the Image Resize Calculator helps you hit a target resolution before printing.
Frequently Asked Questions
What is the difference between DPI and PPI?
PPI (pixels per inch) describes how densely pixels are packed on a screen or in a digital image; DPI (dots per inch) describes how many ink dots a printer lays down per inch. They are often used interchangeably when working out print size, because the arithmetic is the same: print inches = pixels ÷ resolution. Strictly, an image has a PPI and a printer has a DPI.
What DPI should I print at?
300 DPI is the standard for photo-quality prints held at reading distance. Large posters and banners viewed from further away look fine at 150 DPI or even less, because your eye can't resolve the extra detail. Higher DPI needs more pixels: doubling DPI quadruples the pixel count required for the same physical size.
How many pixels do I need for a 6×4 inch print?
Multiply each side by your target DPI. At 300 DPI a 6×4 inch print needs 1800×1200 pixels (about 2.2 megapixels); at 150 DPI it needs 900×600. Switch to the 'print size → required pixels' mode above, enter the size and DPI, and it works out the resolution for you.
Why is 1 inch equal to 2.54 cm here?
That is the exact definition of an inch in the metric system, so all inch-to-centimetre conversions on this page use it. Enter a print size in centimetres and the tool divides by 2.54 to get inches before applying the DPI, so you can plan prints in whichever unit your lab uses.
Educational estimate only. A printer’s true output also depends on its driver, interpolation, and paper.