Free Online Calculators
Diagonal + aspect ratio → width, height, PPI
Screen size: diagonal and aspect ratio give width and height (16:9: width = diagonal × 0.872); the other way round, diagonal = √(width² + height²). A 55-inch TV is 47.9 × 27 in. The calculator also gives PPI and viewing distance.
A 55-inch TV (16:9) measures 47.9 × 27 in (121.8 × 68.5 cm). The other way round, a screen 34 cm wide and 27 cm tall has a 43.4 cm diagonal, i.e. 17.1 inches at 5:4. For 4K, sit about 1.2 × the diagonal away — around 5.5 ft from a 55-inch TV.
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| Diagonal | Width | Height | Diagonal in cm | Viewing distance (4K) |
|---|---|---|---|---|
| 13.3 in | 11.6 in (29.4 cm) | 6.5 in (16.6 cm) | 33.8 cm | — |
| 15.6 in | 13.6 in (34.5 cm) | 7.6 in (19.4 cm) | 39.6 cm | — |
| 24 in | 20.9 in (53.1 cm) | 11.8 in (29.9 cm) | 61 cm | — |
| 27 in | 23.5 in (59.8 cm) | 13.2 in (33.6 cm) | 68.6 cm | — |
| 32 in | 27.9 in (70.8 cm) | 15.7 in (39.8 cm) | 81.3 cm | 3.2 ft |
| 43 in | 37.5 in (95.2 cm) | 21.1 in (53.5 cm) | 109.2 cm | 4.3 ft |
| 50 in | 43.6 in (110.7 cm) | 24.5 in (62.3 cm) | 127 cm | 5 ft |
| 55 in | 47.9 in (121.8 cm) | 27 in (68.5 cm) | 139.7 cm | 5.5 ft |
| 65 in | 56.7 in (143.9 cm) | 31.9 in (80.9 cm) | 165.1 cm | 6.5 ft |
| 75 in | 65.4 in (166 cm) | 36.8 in (93.4 cm) | 190.5 cm | 7.5 ft |
| 85 in | 74.1 in (188.2 cm) | 41.7 in (105.8 cm) | 215.9 cm | 8.5 ft |
47.9 in wide and 27 in tall (16:9) for the picture; the set is 0.5–1 in larger with the bezel.
Diagonal = √(width² + height²). For 34 × 27 cm that is 43.4 cm, or 17.1 inches.
About 6.5 ft for 4K (THX, 40° viewing angle) and 8.7 ft for 1080p.
23.5 × 13.2 in (59.8 × 33.6 cm) at 16:9.
Whether you're shopping for a new TV or setting up a monitor, knowing the actual width and height of a screen matters far more than just the diagonal measurement. A 55-inch TV sounds straightforward, but the physical dimensions vary depending on the aspect ratio — a 16:9 widescreen panel and a 4:3 display with the same diagonal will have very different footprints on your wall or desk.
This screen size calculator lets you enter any diagonal size and aspect ratio to get precise width and height values instantly. For example, a 55-inch 16:9 TV measures approximately 47.9 inches wide and 27 inches tall — useful to know before you mount it above a fireplace or order a TV stand. A 27-inch 16:9 monitor comes out to roughly 23.5 × 13.2 inches, helping you plan desk space accurately.
Pixels per inch (PPI) tells you how sharp a screen looks at normal viewing distance. Two monitors can both be 27 inches, but a 1080p panel has around 82 PPI while a 4K panel reaches about 163 PPI — twice as sharp. Enter your screen's resolution alongside the diagonal and the PPI calculator does the math immediately. Higher PPI means crisper text, finer detail in photos, and less visible pixelation when you sit close.
For phones and tablets, PPI is especially critical. A 6.1-inch phone at 2532 × 1170 resolution delivers roughly 460 PPI — well above the threshold where individual pixels become invisible to the human eye at arm's length. For desktop monitors, anything above 90–100 PPI generally looks sharp for everyday use, while graphic designers and video editors often prefer 120 PPI or higher.
At simple-calculator.online, this tool combines dimension calculation, PPI output, and viewing distance recommendations in one place, so you don't need to jump between multiple tools.
Sitting too close to a large screen causes eye strain; sitting too far means losing detail. The recommended viewing distance depends on both screen size and resolution. For a 65-inch 4K TV, the ideal distance is about 6.5 feet (roughly 1.2 × the diagonal, based on THX's 40° viewing angle). For the same size in 1080p, you'd want to sit about 8.7 feet back (roughly 1.6 × the diagonal, SMPTE's 30°) to avoid seeing individual pixels. This calculator shows the 4K viewing distance for screens from 32 inches up, with the 1080p factor noted alongside.
For monitors, the math changes because you're typically seated 20–30 inches away. A 24-inch 1080p monitor at that distance lands right in the comfortable zone for most users. Step up to a 32-inch 4K monitor and that same desk distance still works well, since the higher pixel density keeps everything sharp up close.
No — screen diagonal is always measured across the display panel itself, not the outer frame. The bezel adds extra physical size to the unit, so always check the full product dimensions before purchasing furniture or mounts.
Most modern TVs and monitors use a 16:9 aspect ratio. Ultrawide monitors commonly use 21:9, and some cinema-format displays use 2.39:1. Older televisions and certain tablets use 4:3 or 3:2.
Beyond a certain point, extra PPI offers no visible benefit at your typical viewing distance. Around 300 PPI at 12 inches is considered the threshold for "retina" quality — where pixels are no longer distinguishable by the human eye.