Screen Size Calculator

Screens are sold by one number — the diagonal — but the space a display actually takes up depends on its aspect ratio. This calculator splits a diagonal into width and height using Pythagoras: for a 16:9 panel, width = diagonal × 16/√337 and height = diagonal × 9/√337.

Compare like with like: a 27-inch 16:9 monitor is 59.8 × 33.6 cm, while an old 27-inch 4:3 screen would be much taller and squarer. Enter the diagonal in inches or centimetres and get width, height and area in the same unit.

The formula

Width = d × W/√(W²+H²); Height = d × H/√(W²+H²); Area = Width × Height

Worked example

A 27-inch 16:9 monitor has a viewable area of about 23.53 × 13.24 inches (311.5 sq in) — before bezels.

The example is pre-loaded in the result panel — press Calculate with your own numbers to replace it.

Frequently asked questions

How wide is a 55-inch TV?

A 55-inch 16:9 TV is about 47.94 inches wide and 26.96 inches tall (121.8 × 68.5 cm). Measure your stand or wall space against the width, not the diagonal.

Why do two 27-inch screens have different areas?

Because area depends on shape: for a fixed diagonal, a squarer screen (4:3) has more area than a wide one (21:9). A 27-inch 4:3 screen has about 13% more area than a 27-inch 16:9.

Does the diagonal include the bezel?

Screen size is the viewable panel diagonal; the physical product is a few centimetres larger with bezels and stand. Check the manufacturer's outer dimensions for fitting furniture.

Category: Unit Conversions calculators