Screen Size Calculator
Find a screen's width and height from its diagonal and aspect ratio.
About the Screen Size Calculator
Enter the diagonal in inches and the aspect ratio (16:9 for most TVs and monitors). The calculator gives the visible width and height in inches and centimetres, the screen area, and a drawing to scale.
Screen sizes are measured diagonally, so two screens with the same diagonal but different ratios have different areas. With the aspect ratio known, Pythagoras gives the width and height.
The formula
width = D × r_w ÷ √(r_w² + r_h²)
- D
- diagonal, in inches
- r_w, r_h
- aspect ratio width and height, e.g. 16 and 9
Worked example
A 55-inch 16:9 TV
- √(16² + 9²) = 18.36
- Width: 55 × 16 ÷ 18.36 = 47.9 in (121.8 cm)
- Height: 55 × 9 ÷ 18.36 = 27.0 in (68.5 cm)
Questions people ask
Does this include the frame?
No, it's the visible screen; add the bezel for the cabinet size.
Is a 4:3 screen of the same diagonal bigger?
It has more area: 4:3 is squarer.
Will it fit my wall or cabinet?
Add 1–3 cm on each side for the frame and check the stand's width too.