Screen PPI Calculator

Work out how sharp a screen is. Enter its resolution and diagonal size and the calculator returns pixels per inch and per centimetre, the dot pitch (the distance between pixels), the physical width and height of the visible area, the aspect ratio and the total number of pixels.

Display Info Runs in your browser

Calculate Screen Pixel Density

JavaScript is required. This tool runs in your browser, so please enable JavaScript to use it. The instructions below are still available.

Common screens

Horizontal pixels

Vertical pixels

Diagonal size

Diagonal unit

Inches

Centimetres

How to Use the Screen PPI Calculator

Pick a Common screen or type the horizontal and vertical pixel counts.
Enter the Diagonal size and choose inches or centimetres.
Press Calculate to see PPI, dot pitch and dimensions.

About This Tool

People comparing monitors, laptops and phones before buying, designers preparing artwork for a specific device, and anyone wondering whether a 27-inch 1440p screen is sharp enough.

Input: Resolution and diagonal · Output: PPI, dot pitch, dimensions.

Features and Limitations

Features

PPI and pixels per centimetre with two-decimal precision.
Dot pitch in millimetres, physical width and height, and screen area.
Simplified aspect ratio (16:9, 21:9 …) and total megapixels.
Presets for common monitors, laptops, TVs and phones.

Limitations

Assumes square pixels and that the advertised diagonal is the visible area; some TVs and monitors round the diagonal.
PPI does not account for subpixel layout (PenTile, RGB stripe, WOLED), which also affects perceived sharpness.
Results are computed in your browser; nothing you enter is sent to a server.

Example

A 27-inch 2560 × 1440 monitor has √(2560² + 1440²) = 2937.2 pixels on the diagonal, so 2937.2 ÷ 27 = 108.79 PPI and a dot pitch of 0.2335 mm.

Frequently Asked Questions

How is PPI calculated?

PPI = √(width² + height²) ÷ diagonal in inches. The square root gives the number of pixels along the diagonal.

Is PPI the same as DPI?

Not quite. PPI describes screen pixels; DPI describes printer dots. People often use DPI for screens, but PPI is the correct term.

What PPI is considered sharp?

At normal desk distance about 110 PPI looks clean on Windows and about 220 PPI looks “Retina” sharp. Phones viewed closer need 300+ PPI.

Why does my phone's PPI differ from the spec sheet?

Manufacturers often round the diagonal or measure it including rounded corners. Small differences in the diagonal change the PPI noticeably on small screens.