Screen Size Calculator
Turn a TV or monitor diagonal and aspect ratio into the actual width, height and surface area of the panel.
in
Height: 13.24 in (33.62 cm)
- 1
Normaliser
√(16² + 9²) = 18.3576The hypotenuse of the ratio triangle; scales the diagonal correctly. - 2
Screen height
27 × 9 ÷ 18.3576 = 13.24 - 3
Screen width
27 × 16 ÷ 18.3576 = 23.53
How does this calculator work?
Enter a screen diagonal and aspect ratio to get its true width, height and area. Width equals diagonal times a divided by the square root of a²+b², height swaps in b, and area is width times height. Default ratio is 16:9, and results are shown in both inches and centimetres.
Formula
How this is calculated
A screen is sold by its diagonal (d, in inches), but the diagonal alone does not tell you how wide or tall the panel is — that depends on the aspect ratio a:b (default 16:9 for most TVs and monitors). The diagonal, width and height form a right triangle whose legs are in the ratio a:b, so by similar triangles the width is d × a ÷ √(a² + b²) and the height is d × b ÷ √(a² + b²).
The screen area is simply width × height. Because a single diagonal can be split across many aspect ratios, a wider 21:9 panel of the same diagonal will be longer but shorter and have less area than a 16:9 one, while a squarer 4:3 panel will be taller and have more area. This is why two TVs with the same advertised size can look quite different.
All results are shown in inches and also converted to centimetres (1 inch = 2.54 cm). Inputs must be positive numbers; a zero or negative diagonal or ratio is rejected. The aspect ratio values are unitless, so 16:9 and 32:18 give identical dimensions.
Frequently asked questions
The 27 inches is the diagonal, not the width. For 16:9 the width is about 23.5 inches and the height about 13.2 inches, because the diagonal is the hypotenuse of the width-by-height rectangle.
Multiply any inch dimension by 2.54. The calculator already shows both inch and centimetre values for width, height and area.
Yes. For a fixed diagonal, a squarer ratio like 4:3 yields the largest area, while ultrawide ratios like 21:9 yield less usable area even though they are wider.
Also known as
TG we-Calculate Editorial Team. (2026). Screen Size Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/screen-size-calculator
TG we-Calculate Editorial Team. "Screen Size Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/screen-size-calculator.
TG we-Calculate Editorial Team, "Screen Size Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/screen-size-calculator
@misc{wecalculate_screen_size_calculator, title = {Screen Size Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/screen-size-calculator}}, year = {2026}, note = {TG we-Calculate} }
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