Screen Size Calculator
Enter a screen's diagonal size (in inches) and aspect ratio to calculate the physical width and height of the display in both inches and centimeters. Optionally enter the PPI (pixels per inch) to also see the pixel resolution.
Screen sizes are always advertised as diagonal measurements, which makes it hard to compare screens with different aspect ratios. A 27-inch 16:9 monitor and a 27-inch 21:9 ultrawide have very different actual widths and heights — this calculator shows you the real dimensions.
Useful for choosing monitors, TVs, and projector screens, planning desk setups, comparing screen sizes across different aspect ratios, and calculating the pixel resolution at a given PPI.
By The Paper Room Editorial Team — Converter Tools
Frequently asked questions
Why are screens measured diagonally?▼
Historical convention from CRT TVs, where the diagonal measurement was the simplest way to describe the tube size. The practice stuck, even though it makes direct size comparisons between different aspect ratios misleading.
What is PPI and how does it relate to resolution?▼
PPI (pixels per inch) is the pixel density of a display. Higher PPI means sharper text and images. Resolution = physical dimension in inches x PPI. A 27-inch 16:9 monitor at 109 PPI is 2560x1440, while the same size at 163 PPI is 3840x2160 (4K).
How do I calculate the viewing area?▼
Multiply the calculated width by the calculated height to get the screen area in square inches. Two screens with the same diagonal but different ratios will have different areas — wider aspect ratios have less total area.