PPI Calculator
Calculate the pixel density (PPI) of any screen for free — enter the resolution and diagonal size, or pick a popular phone, laptop, monitor or TV, and get the pixels per inch, dot pitch, physical width and height, aspect ratio, megapixels and how sharp it looks at your viewing distance.
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PPI = √(width² + height²) ÷ diagonal. Pixels per degree estimates sharpness at your viewing distance — around 60 or more means individual pixels are too small to see.
How to calculate PPI
- Pick a device, or enter the width and height in pixels.
- Enter the diagonal size in inches.
- Optionally choose a viewing distance.
- Read the PPI, dot pitch, size and sharpness.
What you can use it for
- Compare monitors and laptops before buying
- Check whether a display counts as “retina” at your distance
- Work out the physical size of a screen
- Design for real device densities
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See all free image tools →Frequently asked questions
How is PPI calculated?
PPI = √(width² + height²) ÷ diagonal in inches. For example, a 27-inch 2560 × 1440 monitor is about 109 PPI.
What is a good PPI?
It depends on distance: phones look sharp above about 300 PPI, laptops above about 200, and desktop monitors above about 110 at normal distances.
What's the difference between PPI and DPI?
PPI is pixels per inch on a screen; DPI is dots per inch for printing. Use our Print Size Calculator for print.