Screen Size Calculator
Real TV and monitor dimensions, instantly.
Enter a screen's diagonal size in inches and its aspect ratio to get the physical width and height. Useful when a TV or monitor will not fit the cabinet, or when comparing how much bigger a 55" really is than a 50". Defaults to the standard 16:9 widescreen ratio.
How it's calculated
Width = diagonal × ratio-width ÷ √(ratio-width² + ratio-height²), and likewise for height — straight from the Pythagorean theorem.
Frequently asked questions
Is a 55 inch TV 55 inches wide?
No — diagonal size is measured corner to corner. A 55" TV is roughly 48" wide and 27" tall in 16:9; our calculator shows the real dimensions.
How do I measure my screen's diagonal?
Measure the visible screen corner to corner with a tape measure, or check the manufacturer's specifications — the advertised size is the screen, not the frame.
Can I use a ratio other than 16:9?
For 4:3, enter 4 and 3 as the ratio. For ultrawide monitors, enter 21 and 9. The math works for any ratio you type.