By Ahsan Khowaja · Updated 27 October 2026
How to use the screen size calculator
- Choose a mode. Width and height from the diagonal is the usual one: it answers "how wide is a 65-inch TV?". Diagonal from the width and height does the reverse, for a screen or a space you've measured with a tape. Compare two screen sizes puts two diagonals side by side and tells you how much bigger one really is.
- Enter the diagonal in inches or centimetres. Advertised screen sizes are the diagonal of the picture area, so a "55-inch" TV has a 55-inch picture corner to corner.
- Pick the aspect ratio. Almost every TV, monitor and laptop made today is 16:9; many laptops and office monitors are 16:10; ultrawide monitors are 21:9 or 32:9; iPads and older screens are 4:3; Surface devices and some laptops are 3:2. Choose "Custom" to type any ratio, such as 64:27 for a 2560 × 1080 panel.
The result gives the width and height in inches and centimetres, the screen area, and a table of other common sizes at the same ratio. The width and height are the picture only; add the bezel and stand from the manufacturer's spec sheet when you're checking whether the screen fits a cabinet or wall space.
The formula
Call the aspect ratio r = width ÷ height (16:9 gives r = 1.778). The diagonal d, width w and height h form a right triangle, so w² + h² = d², and w = r × h. Solving:
- Height = d ÷ √(r² + 1)
- Width = d × r ÷ √(r² + 1)
- Area = width × height
For a 55-inch 16:9 TV: √(1.778² + 1) = √(337 ÷ 81) = 2.0397. Height = 55 ÷ 2.0397 = 26.96 in, width = 55 × 1.778 ÷ 2.0397 = 47.94 in. Check: 47.94² + 26.96² = 2,298 + 727 = 3,025 = 55². Area = 1,292.6 square inches, or 8,339 cm².
For 16:9 you can shortcut: width ≈ 0.8716 × diagonal and height ≈ 0.4903 × diagonal. For 16:10 the factors are 0.8480 and 0.5300; for 4:3 they are exactly 0.8 and 0.6, because 4:3 is a 3-4-5 triangle, so a 20-inch 4:3 screen is 16 × 12 inches on the nose.
TV size calculator: 16:9 TV dimensions
Every current TV is 16:9, so the tv dimensions calculator part is a single table. Figures are the picture area in inches and centimetres, before the frame.
| TV size | Width | Height | Width (cm) | Height (cm) | Area |
|---|---|---|---|---|---|
| 32 in | 27.89 in | 15.69 in | 70.8 cm | 39.8 cm | 437.6 in² |
| 43 in | 37.48 in | 21.08 in | 95.2 cm | 53.5 cm | 790.1 in² |
| 50 in | 43.58 in | 24.51 in | 110.7 cm | 62.3 cm | 1,068.2 in² |
| 55 in | 47.94 in | 26.96 in | 121.8 cm | 68.5 cm | 1,292.6 in² |
| 65 in | 56.65 in | 31.87 in | 143.9 cm | 80.9 cm | 1,805.3 in² |
| 75 in | 65.37 in | 36.77 in | 166.0 cm | 93.4 cm | 2,403.6 in² |
| 85 in | 74.08 in | 41.67 in | 188.2 cm | 105.8 cm | 3,087.2 in² |
So the 55 inch tv dimensions people search for most are about 48 × 27 inches of picture, roughly 122 × 68.5 cm. Many sets are sold as a "class" size, for instance a 55-inch class TV whose measured diagonal is 54.6 inches; the difference is a few millimetres in each direction, but check the spec sheet for the outer dimensions with the bezel before buying a wall mount or furniture.
Monitor size calculator: desks, laptops and ultrawides
Monitors come in more shapes than TVs, which is where the aspect ratio setting earns its place. A 27-inch 16:9 monitor is 23.53 × 13.24 inches (59.8 × 33.6 cm). A 24-inch 16:10 monitor is 20.35 × 12.72 inches, taller than a 24-inch 16:9 (20.92 × 11.77 inches) despite the identical diagonal. A 34-inch 21:9 ultrawide is 31.25 × 13.39 inches, so it is barely taller than a 27-inch 16:9 but almost 8 inches wider; a 49-inch 32:9 super ultrawide is 47.17 × 13.27 inches, the width of two 27-inch monitors side by side.
For a screen size calculator laptop users can trust, apply the same rule with the laptop's panel ratio: a 15.6-inch 16:9 laptop screen is 13.6 × 7.65 inches (34.5 × 19.4 cm), a 14-inch 16:10 screen is 11.87 × 7.42 inches, and a 13.5-inch 3:2 screen (the Surface Laptop shape) is 11.23 × 7.49 inches. The laptop itself is larger than its screen by the bezel and the keyboard deck, which the spec sheet lists.
Note that marketed ultrawide ratios are rounded. A 2560 × 1080 or 3440 × 1440 panel is 64:27 (2.370:1), not exactly 21:9 (2.333:1). The difference is small (a 34-inch screen comes out 31.33 × 13.22 inches at 64:27 against 31.25 × 13.39 at 21:9), but if you need the exact figure, choose "Custom" and enter 64 and 27.
Projector screen size calculator
Projector screens are quoted the same way, by the diagonal and ratio, but the sizes are larger: a 100-inch 16:9 screen is 87.16 × 49.03 inches (221 × 125 cm), and a 120-inch one is 104.59 × 58.83 inches (266 × 149 cm). Use the calculator to check that the width fits your wall and the height clears your furniture. A projector screen size calculator based on room size also needs the seating distance, which the TV viewing distance calculator covers: it works out which diagonal fills a comfortable share of your view from where you sit. The throw distance, how far the projector must sit from the screen for a given image width, depends on the lens and is listed in the projector's manual.
Screen size comparison: why area matters more than the diagonal
The compare mode shows the difference by area, because the diagonal understates how much bigger a screen is. Area grows with the square of the diagonal when the shape stays the same, so a 65-inch TV has (65 ÷ 55)² = 1.397 times the area of a 55-inch, that is 39.7% more screen, not the 18% the diagonals alone suggest. Going from 55 to 75 inches almost doubles the area (+86%).
Screen size comparison across different ratios is where the calculator helps most. A 34-inch 21:9 ultrawide sounds much bigger than a 27-inch 16:9, but it has 418.6 square inches against 311.5, about 34% more, and it is only 0.15 inches taller. Two 27-inch 16:9 monitors (623 in²) give you more picture than one 34-inch ultrawide. The same mode works for phones: compare a 6.1-inch and a 6.7-inch 19.5:9 screen by entering the ratio as custom, and you'll see the larger one has about 21% more area.
Screen size in pixels vs inches
The diagonal says nothing about resolution. A 27-inch screen can be 1920 × 1080, 2560 × 1440 or 3840 × 2160; all three are 23.53 × 13.24 inches, the pixels are just smaller. Screen size in pixels is set by the panel's resolution, and the two are linked by pixel density: pixels per inch = diagonal in pixels ÷ diagonal in inches. The PPI calculator does that calculation, and the pixels to inches converter turns a pixel measurement into a physical length at a given density.
If you only know a screen's resolution and want its shape, the aspect ratio calculator reduces 1920 × 1080 to 16:9 and compares it with the standard ratios; it also works as a height to width ratio calculator for any pair of numbers.
