The diagonal is a misleading measure of screen size when comparing the size of screens with different aspect ratio.
For example, if you have a 19 inch screen with a 5:4 aspect ratio and you want to switch to a widescreen monitor with at least the same screen height, how big should the diagonal be? Using the table below, you can find out.
The table shows width×height=area for some common screen sizes and aspect ratios.
| 5:4 | 4:3 | 16:10 | 16:9 | |
|---|---|---|---|---|
| 17 | 13.3×10.6=141.0 | 13.6×10.2=138.7 | 14.4×9.0=129.9 | 14.8×8.3=123.5 |
| 18 | 14.1×11.2=158.0 | 14.4×10.8=155.5 | 15.3×9.5=145.6 | 15.7×8.8=138.4 |
| 19 | 14.8×11.9=176.1 | 15.2×11.4=173.3 | 16.1×10.1=162.2 | 16.6×9.3=154.3 |
| 20 | 15.6×12.5=195.1 | 16.0×12.0=192.0 | 17.0×10.6=179.8 | 17.4×9.8=170.9 |
| 21 | 16.4×13.1=215.1 | 16.8×12.6=211.7 | 17.8×11.1=198.2 | 18.3×10.3=188.4 |
| 22 | 17.2×13.7=236.1 | 17.6×13.2=232.3 | 18.7×11.7=217.5 | 19.2×10.8=206.8 |
| 23 | 18.0×14.4=258.0 | 18.4×13.8=253.9 | 19.5×12.2=237.8 | 20.0×11.3=226.0 |
| 24 | 18.7×15.0=281.0 | 19.2×14.4=276.5 | 20.4×12.7=258.9 | 20.9×11.8=246.1 |
| 25 | 19.5×15.6=304.9 | 20.0×15.0=300.0 | 21.2×13.2=280.9 | 21.8×12.3=267.1 |
| 26 | 20.3×16.2=329.8 | 20.8×15.6=324.5 | 22.0×13.8=303.8 | 22.7×12.7=288.9 |
| 27 | 21.1×16.9=355.6 | 21.6×16.2=349.9 | 22.9×14.3=327.6 | 23.5×13.2=311.5 |
| 28 | 21.9×17.5=382.4 | 22.4×16.8=376.3 | 23.7×14.8=352.4 | 24.4×13.7=335.0 |
| 32 | 25.0×20.0=499.5 | 25.6×19.2=491.5 | 27.1×17.0=460.2 | 27.9×15.7=437.6 |