Physical display dimensions and fit
Monitor Size Calculator
Find a monitor’s viewable width, height and area from its diagonal, calculate the diagonal from measurements, find the largest screen that fits a space, or compare two display sizes.
Monitor size formulas
Manufacturers normally state the viewable diagonal, not the monitor’s outside dimensions. For aspect ratio a:b and diagonal d, the viewable dimensions are:
width = d × a ÷ √(a² + b²)height = d × b ÷ √(a² + b²)area = width × height
If width and height are known, diagonal = √(width² + height²). The fit mode first subtracts the bezel allowance from both sides, then scales the chosen aspect ratio to the tighter of the available width and height.
Physical size is not resolution. Two 27-inch monitors can have identical viewable dimensions but different pixel counts and sharpness. Use the PPI calculator for pixel density.
Checked examples
| Mode | Inputs | Checked result |
|---|---|---|
| Dimensions | 27 in, 16:9 | 23.533 in wide × 13.237 in high; 311.501 in² |
| Diagonal | 23.53 × 13.24 in | 26.999 in diagonal; displayed ratio about 1.777:1 |
| Fit | 30 × 18 in space, 16:9, 0.5 in bezel per side | 33.273 in maximum viewable diagonal; 30 × 17.313 in estimated outside size |
| Compare | 27 vs 32 in, both 16:9 | The 32 in screen has 40.466% more viewable area |
How to measure and interpret the result
- Measure only the lit, viewable panel for width and height. Do not include the bezel.
- A listed 27-inch monitor is approximately 27 inches corner to corner; manufacturing tolerances and rounded marketing sizes can cause small differences.
- The same diagonal at a wider aspect ratio is wider and shorter. Compare area only when that difference matches your intended use.
- For a shelf, cabinet or desk fit, check the manufacturer’s full product width, height, stand depth, ventilation clearance and cable clearance before buying.
- The bezel input is an estimate per side. It does not model asymmetrical borders, curved panels, stands or mounting hardware.
- Inputs must be finite numbers within the displayed limits. Aspect-ratio values and dimensions must be greater than zero; bezel allowance may be zero.