What this calculator does
Screen viewing distance works out recommended seating distance from a screen size and target field of view. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulawidth = diagonal × ratio/√(ratio²+1); distance = (width/2) / tan(angle/2)
The inputs explained
| Field | What to enter |
|---|---|
| Screen diagonal (in) | A number, measured in in. Starts at 65. |
| Aspect ratio | Choose from 4:3, 16:9, 21:9 ultrawide, 2.39:1 cinema. |
| Target viewing angle | Choose from 30° – SMPTE cinema reference, 36° – THX 4K recommendation, 40° – THX immersive recommendation. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with screen diagonal
Every other input is held at the calculator’s starting values while screen diagonal varies. Select any row to load that scenario into the calculator.
How the answer changes with screen diagonal