PPI Calculator (Pixel Density)
Calculate pixels per inch (PPI), pixels per cm and dot pitch from a screen resolution and diagonal size in inches or cm. Also shows physical width and height.
Results
What is PPI Calculator?
Works out the pixel density of a display from its resolution and diagonal: pixels per inch, pixels per centimetre, dot pitch in millimetres, the diagonal in pixels, total pixels and the physical width × height of the panel.
How to use PPI Calculator
- Enter the horizontal and vertical resolution in pixels, or pick a preset (HD, Full HD, QHD, 4K).
- Enter the Diagonal size and choose inches or centimetres.
- Read the PPI and the other results.
Example
1920 × 1080 px, 24 inch
91.79 PPI, dot pitch 0.2767 mm, diagonal 2,202.91 px
When to use PPI Calculator
Use it to compare monitors, phones or laptops, to judge sharpness at a viewing distance, or to set up print previews. It describes the panel itself; operating-system scaling (for example 150%) does not change the physical PPI.
How PPI Calculator works
Diagonal in pixels = √(width² + height²) (Pythagoras). PPI = diagonal in pixels ÷ diagonal in inches. Dot pitch = 25.4 mm ÷ PPI, the distance between pixel centres. Physical width = diagonal × width ÷ diagonal in pixels, and the same for height. Centimetre input is converted with 1 in = 2.54 cm. Square pixels are assumed, which is true for practically all modern displays.
Common Use Cases
- Comparing a 27" 1440p monitor with a 27" 4K one
- Checking phone screen sharpness
- Estimating physical screen width from the diagonal
- Finding dot pitch for a display spec sheet
FAQs
Is PPI the same as DPI?
Not exactly. PPI describes pixels on a screen; DPI describes ink dots of a printer. They are often used interchangeably for screens.
What PPI looks sharp?
It depends on distance. Around 90–110 PPI is typical for desktop monitors at arm's length, while phones viewed closer use 300–500 PPI.
Why is my measured diagonal slightly different?
Advertised diagonals are often rounded (a "27-inch" panel may be 27.0 or 26.9 inches of visible area), which changes the PPI slightly.