Screen Size Calculator
Choose what you know: the diagonal, the width, the height, or both the width and the height. Add the aspect ratio (16:9, 21:9, 4:3 or any ratio you type) and the calculator gives the other sizes, the screen area and the diagonal angle, in inches, centimeters and millimeters. A small drawing shows the shape of the screen. Use it to check whether a TV fits a wall, how wide a monitor really is, or what a quoted diagonal means in width and height. Everything runs in your browser.
| Size | in | cm | mm |
|---|---|---|---|
| Diagonal | 55 | 139.7 | 1397 |
| Width | 47.94 | 121.76 | 1217.59 |
| Height | 26.96 | 68.49 | 684.89 |
The diagonal, width and height of a flat screen make a right triangle, so diagonal squared equals width squared plus height squared, and width divided by height is the aspect ratio. With the diagonal and the ratio, the width is the diagonal times the ratio width divided by the square root of (ratio width squared plus ratio height squared), and the height is found the same way. These are the sizes of the visible panel. A TV or a monitor is larger than that because of its frame, and a quoted diagonal can be rounded. Everything runs in your browser.
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Math & MoneyAbout the Screen Size Calculator
The diagonal, the width and the height of a flat screen make a right triangle, so diagonal squared equals width squared plus height squared, and the aspect ratio is the width divided by the height. Given the diagonal and a ratio of w:h, the width is the diagonal times w divided by the square root of (w squared plus h squared), and the height is the diagonal times h over the same root. For example, a 55 inch 16:9 screen is 47.94 inches wide and 26.96 inches tall (about 121.8 by 68.5 cm), with an area of 1,292.58 square inches. A 27 inch 16:9 monitor is 23.53 by 13.24 inches, and a 32 inch one is 27.89 by 15.69 inches. A 34 inch screen of 21:9 is 31.25 inches wide and 13.39 inches tall when 21:9 is taken as written, although many ultrawide panels are really 64:27, so type the exact ratio if you know it. Going the other way, a screen 48 inches wide at 16:9 has a diagonal of 55.07 inches. These are the sizes of the visible panel. The frame and stand make the whole device larger, and a quoted diagonal can be rounded, so check the maker size if the fit is tight.
How do I find the width and height of a screen from its diagonal?▾
Multiply the diagonal by the ratio width and divide by the square root of the ratio width squared plus the ratio height squared. Do the same with the ratio height for the height. For 16:9 the width is 0.8716 times the diagonal and the height is 0.4903 times the diagonal.
Does a 55 inch TV measure 55 inches wide?▾
No. The 55 inches is the diagonal. A 16:9 screen with a 55 inch diagonal is about 47.94 inches wide and 26.96 inches tall.
Is the size the same as the real TV size?▾
It is the size of the visible panel only. The frame, the stand and any speakers add to the outside size, so use the maker dimensions when you plan space on a wall or a desk.
What aspect ratio should I enter?▾
Use the ratio of the screen: 16:9 for most TVs and monitors, 16:10 for many laptops, 21:9 or 32:9 for ultrawide monitors. If you know the resolution, its width to height ratio is the aspect ratio, so 2560 x 1440 is 16:9.
Is my data uploaded?▾
No. The calculation runs in your browser and nothing you enter is sent anywhere.