Screen Size Calculator
The width, height and area of a TV, monitor or phone screen from its diagonal size and aspect ratio, or the diagonal from its width and height.
Result
Width: 23.53 in
The picture area only; the frame around it adds to the outside size.
- Height
- 13.24 in (33.62 cm)
- Screen area
- 311.5 in² (2,009.7 cm²)
- Width ÷ height
- 1.7778
https://calcgallery.com/everyday-math/screen-size-calculator/
Results follow the mathematical operation and values shown. Check that you selected the intended operation, convention and dataset type before relying on the result. Read the full disclaimer
How to use the Screen Size Calculator
- Enter the screen’s advertised size, the diagonal, in inches or centimetres.
- Enter its aspect ratio, 16 and 9 for most TVs and monitors, then read the width, height and area.
- To go the other way, choose the diagonal and enter the measured width and height of the picture.
The formula
A screen is a rectangle, and its quoted size is the diagonal. With an aspect ratio of a:b, the width and height are the two legs of a right triangle in that ratio:
k = diagonal ÷ √(a² + b²)width = a × kheight = b × karea = width × heightThe reverse is Pythagoras directly: diagonal = √(width² + height²). A 20 by 15 inch picture has a 25-inch diagonal.
What the page does not cover
The size is for the picture area of a flat panel. A curved screen is measured along the curve by some makers, and a phone with rounded corners is often quoted as if the corners were square, so the real picture can be slightly smaller. The page gives dimensions only; it does not recommend a size for a room or a seating distance. For how finely the pixels are packed on the screen, use the PPI calculator.
With your numbers
- √(16² + 9²) = 18.3576
- width = diagonal × 16 ÷ 18.3576, height = diagonal × 9 ÷ 18.3576
Quick reference
The picture area only; the frame around it adds to the outside size.
| Example | Result |
|---|---|
| 27 in, 16:9 | Width: 23.53 in |
| 65 in TV, 16:9 | Width: 56.65 in |
| 34 in, 21:9 | Width: 31.25 in |
| 13.3 in, 16:10 | Width: 11.28 in |
| 24 in, 4:3 | Width: 19.2 in |
| 80 cm, 16:9 | Width: 69.73 cm |
| 20 × 15 in | Diagonal: 25 in |
Common questions about the Screen Size Calculator
- How is a screen size measured?
- Corner to corner across the picture, not across the frame. A 65-inch TV has a picture 65 inches from one corner to the opposite corner; the bezel around it makes the set itself a little larger, so allow for that when fitting a TV into a cabinet or alcove.
- How wide is a 65-inch 16:9 TV?
- About 56.7 inches wide and 31.9 inches tall, picture only. The diagonal is the hypotenuse of a right triangle whose legs are in the ratio 16 to 9, and √(16² + 9²) is about 18.36, so the width is 65 × 16 ÷ 18.36 and the height 65 × 9 ÷ 18.36.
- Why does a 16:9 screen have less area than a 4:3 screen of the same size?
- Because a longer, thinner rectangle fits less area under the same diagonal. At 27 inches a 16:9 picture is about 311 square inches, while a 4:3 picture is about 350. Comparing screens of different shapes by diagonal alone understates how different they are.
- Which aspect ratio should I enter?
- The one on the specification sheet. Most TVs and monitors are 16:9, many laptops are 16:10 or 3:2, ultrawide monitors are about 21:9, and phones vary. If you know the resolution, such as 2560 × 1440, the aspect ratio calculator reduces it for you: that one is 16:9.