Where 21:9 is used
Ultrawide monitors are marketed as 21:9, although many panels are 3440 × 1440, which is closer to 2.39:1. 7:3 is the same shape as 21:9. Typical uses: Ultrawide monitors, cinematic video and widescreen gaming.
Common 21:9 resolutions
| Width × height | Name |
|---|---|
| 2560 × 1080 px | UW-FHD (sold as 21:9) |
| 2520 × 1080 px | Exact 21:9 at 1080 tall |
| 3440 × 1440 px | UW-QHD (sold as 21:9) |
| 5120 × 2160 px | 5K ultrawide |
How to calculate 21:9 dimensions
Height = width × 9 ÷ 21. Width = height × 21 ÷ 9. Round to whole pixels; many video encoders also need even numbers.
CSS for a 21:9 box
.media { aspect-ratio: 21 / 9; width: 100%; }