Monitor Dimensions Calculator
Diagonal and aspect ratio give the physical width, height and viewable area. Add the resolution to get pixel density and pixel pitch. Every field is an independent input.
- Physical width
- —
- Physical height
- —
- Viewable area
- —
- Diagonal
- —
- Pixel density
- —
- Pixel pitch
- —
- Aspect ratio
- —
- Pixels
- —
Same diagonal, different panel
The diagonal is one number, the screen is not. Every row below uses the diagonal above; the highlighted row is the ratio you picked.
| Ratio | Width | Height | Area | Area vs yours |
|---|
How this is calculated
A panel is a right triangle: width, height and diagonal satisfy W² + H² = D². With the ratio AR = W ÷ H, the height follows directly from the diagonal:
H = D ÷ √(AR² + 1) · W = AR × H · area = W × H
Pixel density uses the same diagonal in pixels: PPI = √(pxW² + pxH²) ÷ D. Pixel pitch is the width of one pixel in millimetres, 25.4 ÷ PPI.
The ratio and the resolution are separate things and this page keeps them separate. A 2560 × 1440 panel is exactly 16:9. A 3440 × 1440 panel is 2.389:1, which is why 21:9 is only an approximation for it — the calculator shows the ratio you enter, not the one the marketing name suggests.
Worked examples
Two fixed pairs have their own pages when the sizes are already decided: 27 inch vs 32 inch monitor keeps both panels editable and lists every difference in inches and percent, and 24 inch vs 27 inch monitor does the same for the step below it.
Put the first two side by side and the diagonal stops being a shortcut. A 34-inch ultrawide is 7.72 inches wider than a 27-inch 16:9 and only 0.15 inches taller, so it adds desk width and almost no height. Hold the diagonal fixed instead — 27 inches at 21:9 against 27 inches at 16:9 — and the wider panel is 5.46% wider, 19.65% shorter and 15.27% smaller in area.
What this page supports
- Diagonal: 1 to 200 inches, or the same in centimetres. Converted at 2.54 cm per inch.
- Ratio: 16:9, 16:10, 21:9, 32:9, 4:3, 5:4, 1:1, plus any custom width ÷ height down to two decimals.
- Resolution: nine common monitor and TV sizes, or any custom pixel grid.
- PPI: either derived from diagonal and resolution, or typed in as its own input — in which case the diagonal is derived from resolution and PPI.
Not included, on purpose: bezel width, curvature and viewing distance. A curved panel has the same diagonal, width and height as a flat one at the same ratio; only its depth behind the desk changes. Viewing distance is a comfort rule, not a dimension, so it has its own page: tv viewing distance turns a diagonal, a ratio and a seat into the field of view the screen fills.
Monitor dimension questions
How wide is a 27 inch monitor?
A 27-inch 16:9 panel is 23.53 inches wide and 13.24 inches tall, with 311.5 square inches of viewable area. A 27-inch 21:9 panel is 24.82 inches wide and 10.64 inches tall.
Does the diagonal include the bezel?
No. The advertised number is the viewable panel, corner to corner. The plastic frame adds width and height on top of the figures here, which is why a monitor measured on a desk often comes out larger than the spec sheet.
Why is my 3440 × 1440 monitor not exactly 21:9?
3440 ÷ 1440 = 2.389. The 21:9 name is a rounded label. If you enter 21:9 you get the 21:9 geometry; if you enter 2.389 you get your actual panel. This calculator accepts either.
Is a bigger diagonal always a bigger screen?
Not in area. Diagonal fixes the distance across the corners, not the shape. At the same diagonal, moving from 16:9 to 21:9 costs 15.27% of the area while adding 5.46% of width.
What is pixel pitch and why does it matter?
Pixel pitch is the physical width of one pixel, in millimetres. At 2560 × 1440 on 27 inches it is 0.233 mm, and 0.156 mm on a 4K 27-inch panel. Smaller pitch means finer detail for the same viewing distance; it is the number people compare when they talk about text looking sharp.
Do these numbers work for a TV as well?
Yes. The geometry is identical; only the diagonal range changes. The same inputs return the dimensions of a TV panel, a laptop display or a phone screen.
Method note
Every figure on this page is arithmetic on the definition of a rectangle: the Pythagorean relation, the ratio, and the pixel grid. Nothing is estimated, nothing is sampled from a database, and no manufacturer specification is assumed. You can reproduce any output with the three formulas in the first section, and the copy button writes the same numbers the screen shows.