MotionShine01 / PPI
Pixel density
The diagonal in pixels (from width and height) divided by the diagonal in inches.
Free tool
PPI calculator, how sharp a screen is.
Type a screen's resolution and diagonal size, or pick a common laptop, monitor or phone, to see its pixels per inch, the dot pitch, its width and height in inches and centimetres, and its aspect ratio. Use My screen to fill in the resolution of the screen you are on; a browser cannot know the physical size, so type that from the box or the spec sheet.
Presets are examples of common sizes; check your own model's specs.
Worked out in your browser. Nothing is sent anywhere.
The maths
Diagonal pixels over diagonal inches.
02 / Dot pitch
Pixel size
The distance between pixels in millimetres: 25.4 divided by the PPI.
03 / Size
Width and height
The physical width and height from the diagonal and the aspect ratio.
Questions
Good to know.
How do I calculate PPI?
PPI = √(width² + height²) ÷ diagonal in inches. A 27" 2560 x 1440 screen is about 109 PPI.
What is a good PPI?
It depends on distance. Phones held close use 400 or more; desktop monitors at arm's length look sharp from about 110 to 220.
What is the difference between PPI and DPI?
PPI is pixels on a screen; DPI is dots of ink a printer lays down. People often mix them up.
Can the page measure my screen size?
No. Browsers do not know physical size, only the resolution.
Is anything sent anywhere?
No.