๐ฅ๏ธ Screen Size Calculator
Calculate a screen's actual width and height โ in inches and centimeters โ from its diagonal size (in inches, as commonly listed on monitor and TV spec sheets) and aspect ratio. Useful for checking whether it'll fit your desk or comparing screen sizes.
How to use
- Enter the diagonal size in inches.
- Choose an aspect ratio (16:9, 4:3, etc.).
- The width, height, and area are calculated automatically.
How the calculation works
Monitor and TV sizes are quoted as the diagonal in inches. Width and height follow from that diagonal and the aspect ratio (width:height) by Pythagoras's theorem. For an aspect ratio a:b, the diagonal is in proportion โ(aยฒ + bยฒ). With a diagonal of D inches, width = D ร a รท โ(aยฒ + bยฒ) and height = D ร b รท โ(aยฒ + bยฒ). For 16:9, โ(16ยฒ + 9ยฒ) = โ337 โ 18.36. The same diagonal gives different areas at different aspect ratios. An ultra-wide 21:9 monitor is shorter and has less screen area than a 16:9 monitor of the same quoted size, so inches alone are not a fair comparison.
Worked example
A 27-inch 16:9 monitor 1. โ(16ยฒ + 9ยฒ) = โ337 โ 18.358 2. Width: 27 ร 16 รท 18.358 โ 23.53 in (about 59.8 cm) 3. Height: 27 ร 9 รท 18.358 โ 13.24 in (about 33.6 cm) When planning desk space, add the bezel and stand to these panel dimensions.
Things to be aware of
- The result is the visible panel area; the bezel and stand are not included.
- On curved monitors the diagonal may be measured along the curve, so it differs slightly from the straight-line distance.
- Area varies with aspect ratio at the same diagonal; compare like with like.
- Phones have rounded corners and notches, so the usable display is smaller than the calculated area.
FAQ
What's the actual size of a 27-inch monitor?
At a 16:9 aspect ratio, a 27-inch diagonal works out to about 23.5" ร 13.2" (59.7cm ร 33.6cm).
Can this be used for phone screen sizes too?
Yes โ choosing the right aspect ratio lets you estimate phone and tablet screen dimensions too.
Does this include the bezel?
No โ this calculates only the display area (panel) size, not the surrounding bezel.