Screen Size Calculator
A TV's inches are the diagonal, not the width. Enter the diagonal and aspect ratio to see how much wall it'll really cover.
How it works
Screen sizes are measured corner to corner, so a 55-inch label doesn't tell you the width. The calculator uses the aspect ratio and a bit of Pythagoras to split that diagonal into width and height.
For a 16:9 screen, the diagonal spans a 16-by-9 rectangle. A 16:9 55-inch TV is about 48 inches wide and 27 inches tall — roughly 122 by 68 cm once you convert.
Swap the ratio for ultrawide monitors (21:9), older 4:3 sets, or 16:10 laptops, and the width and height shift even when the diagonal stays the same. That's why two same-size screens can fit spaces very differently.
Frequently asked questions
How wide is a 55-inch TV?
A 16:9 55-inch TV is about 48 inches wide and 27 inches tall, or roughly 122 by 68 cm. Measure your stand or wall against the width, not the 55-inch diagonal.
Why isn't the screen 55 inches wide?
The 55 inches is the diagonal, measured across the corners. The actual width is shorter because the diagonal cuts through the rectangle — the aspect ratio decides how the size splits.
What aspect ratio should I pick?
Most TVs and modern monitors are 16:9. Ultrawide gaming monitors are usually 21:9, many laptops are 16:10, and older screens or some tablets use 4:3, so match the tool to your device.
Does this include the bezel?
The numbers cover the viewable screen only, not the frame around it. Add a little for the bezel and stand when you're checking whether a set fits a cabinet or recess.