PPI Calculator
Enter a resolution and diagonal screen size to get pixels per inch, physical dimensions and dot pitch — updated as you type.
Resolution + diagonal → pixel density, instantly
Enter the panel's native resolution from its specifications and its diagonal in inches, or choose a preset. Browser dimensions and DPR cannot reliably identify native resolution. Calibrate the ruler to estimate the current screen's diagonal.
Why pixel density matters
Two displays with identical resolution can look completely different: 1920 × 1080 is razor-sharp on a 6-inch phone (~367 PPI) but visibly pixelated on a 27-inch monitor (~82 PPI). PPI is the number that captures that difference. Compare real devices in ourphone screen size chart, or check what your own display reports with the screen size checker. For a desk display, use the monitor size and resolution guide to combine PPI with physical width, viewing distance and operating-system scaling.
Frequently asked questions
›How is PPI calculated?
PPI = diagonal resolution in pixels ÷ diagonal size in inches. The diagonal in pixels is √(width² + height²). The calculator above shows the formula worked through your exact numbers.
›What is a good PPI?
There is no universal threshold. Viewing distance, eyesight, contrast and content affect perceived sharpness. Compare PPI at the distance you will actually use the screen, and consider OS scaling for readable text.
›Is PPI the same as DPI?
They're often used interchangeably, but strictly PPI describes display pixel density while DPI (dots per inch) describes printer dot density. For screens, PPI is the correct term.
›Does a higher PPI make text smaller?
Higher PPI packs the same pixel count into less physical space. Operating-system scaling can enlarge text and controls to compensate, but the result depends on the selected scale and the application.
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- Screen Size ComparisonCompare display dimensions, complete video pictures and A4 page size. View screens side by side or estimate physical size after calibration.
- Phone Screen SizesPhone screen size chart with display inches, resolution, PPI and aspect ratio; viewport references where available for tracked iPhone, Galaxy and Pixel phones, including foldables.
- Device Pixel Ratio CheckerCheck your device pixel ratio (DPR) instantly and understand the difference between CSS pixels and physical pixels, with visual examples.