Pixels per inch from resolution and screen size.
Free to use, no sign-up required. PPI Calculator is one of 198 tools built into Xenition, alongside a chat that can use them for you.
Calculates a screen’s pixel density in pixels per inch from its resolution and diagonal size, along with dot pitch and megapixels.
The diagonal in pixels is √(width² + height²). PPI = diagonal pixels ÷ diagonal inches. Dot pitch, the distance between pixel centres, is 25.4 ÷ PPI in millimetres. Megapixels = width × height ÷ 1,000,000.
A 24-inch 1920 × 1080 monitor has a diagonal of 2,203 pixels, giving 91.8 PPI, a 0.277 mm dot pitch and 2.07 megapixels. A 27-inch 2560 × 1440 monitor comes to 108.8 PPI.
They are often used interchangeably for screens, but strictly PPI counts pixels on a display and DPI counts ink dots from a printer. For monitors and phones, PPI is the right measure.
It depends on viewing distance. Around 90–110 PPI suits a desktop monitor at arm’s length, while phones held closer usually need 300 PPI or more for pixels to disappear.
You do not have to open PPI Calculator to use it. Ask Xenition in plain language and it runs the right tool, then carries the answer into whatever you are working on — a document, a spreadsheet, a deck.