Screen Size Calculator
From diagonal and aspect ratio to screen width, height and area.
Quick answer
- Formula: Width = d × W/√(W²+H²); Height = d × H/√(W²+H²); Area = Width × Height
- Worked example — Width: 23.53 (full example below).
Screen Size Calculator
| Width | 23.53 |
| Height | 13.24 |
| Screen area | 311.5 |
| Summary | 27 in diagonal (16:9) = 23.53254 × 13.237053 in |
A 27-inch 16:9 monitor has a viewable area of about 23.53 × 13.24 inches (311.5 sq in) — before bezels.
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
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
Sources & methodology
This calculator applies the formula shown on this page exactly as written, using the standard definitions for its inputs. Results are computed from the values you enter — no data is stored — and are rounded only for display.
Content last reviewed by CalcHub Editorial.
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