PPI Calculator
Enter the width and height of the screen in pixels and its diagonal in inches or centimeters, and the calculator returns the pixel density in pixels per inch (PPI) and per centimeter, the pixel pitch in millimeters, the physical width and height, and the total pixel count. A second mode starts from a density you know, such as 326 PPI, and works out the screen size. Quick buttons fill in common resolutions. Everything runs in your browser.
Pixel density is the number of pixels along the diagonal divided by the length of the diagonal: PPI = square root of (width squared plus height squared) in pixels, divided by the diagonal in inches. Pixel pitch is the other way round, 25.4 mm divided by the PPI. A higher density means smaller pixels and a sharper picture at the same viewing distance, but how sharp a screen looks also depends on how far away you hold it. The sizes shown assume square pixels and the visible panel only. Everything runs in your browser.
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Format ConversionAbout the PPI Calculator
Pixel density is the number of pixels along the diagonal divided by the length of the diagonal. The pixels along the diagonal are the square root of (width squared plus height squared), so a 1920 x 1080 screen has about 2,203 of them. On a 24 inch diagonal that is 91.79 PPI, and the pixel pitch, the distance between pixel centers, is 25.4 divided by 91.79, or 0.2767 mm. A 2560 x 1440 screen at 27 inches has 108.79 PPI (pitch 0.2335 mm), and a 3840 x 2160 screen at 27 inches has 163.18 PPI (pitch 0.1557 mm). The same 1920 x 1080 picture on a 27 inch screen drops to 81.59 PPI, and on a 15.6 inch laptop it rises to 141.21 PPI. In the reverse mode, 2560 x 1440 pixels at 109 PPI need a diagonal of about 26.95 inches. A higher density means smaller pixels and a sharper picture at the same distance, but how sharp it looks also depends on how far away you are. The physical size assumes square pixels and counts the visible panel only.
How is PPI calculated?▾
Take the square root of the width in pixels squared plus the height in pixels squared, then divide by the diagonal in inches. A 1920 x 1080 screen with a 24 inch diagonal has 91.79 PPI.
What is pixel pitch?▾
It is the distance from the center of one pixel to the center of the next, in millimeters. It equals 25.4 divided by the PPI, so a smaller pitch means a denser screen.
Is PPI the same as DPI?▾
They are often mixed up. PPI counts the pixels of a screen or a digital image per inch. DPI counts the dots a printer puts down per inch, so use PPI for screens.
What is a good PPI?▾
It depends on the viewing distance. A desktop monitor is viewed from further away than a phone, so a lower density can look sharp on it. Compare screens of the same type and distance rather than chasing one number.
Is my data uploaded?▾
No. The calculation runs in your browser and nothing you enter is sent anywhere.