What is a 21:9 aspect ratio?
The 21:9 aspect ratio is an ultra-wide ratio generally used to represent ultrawide films and monitors, even though they aren't an exact match.
It became a marketing term because it has the same denominator as the standard HDTV 16:9 aspect ratio. The ratios that are also considered as "21:9" are:
- 64:27 (2560x1080)
- 43:18 (13340x1440)
- 12:5 (3840x1600)[1].
Example 1
LG advertised its 29-inch LG 29WN600 monitor[2] and many other models as ultrawide monitors with an aspect ratio of 21:9, while it has a resolution of WFHD 2560 x 1080 with an exact ratio of 64:27.
Example 2
The Samsung 34" QLED Ultra WQHD curved monitor[3] is advertised as a 21:9 aspect ratio, while it has a resolution of WQHD 3440x1440 with an exact ratio of 43:18.
The aspect ratio has a standard format of 21:9 or W:H, where W is the width, and H is the height of an image, screen, or container. In digital space, the measurement unit is in pixels. You can pronounce it "twenty-one by nine" or "twenty-one to nine" aspect ratio.
Common 21:9 resolutions
Here are the 21:9 resolutions you frequently see on cinema films and monitors.
| Resolution | Width | Height | Real Aspect Ratio | Standard |
|---|---|---|---|---|
| 1680 x 720 | 1680 | 720 | 21:9 | WHD |
| 1920 x 800 | 1920 | 800 | 12:5 | |
| 2520 x 1080 | 2520 | 1080 | 21:9 | WHD |
| 2560 x 1080 | 2560 | 1080 | 64:27 | WFHD+ |
| 2880 x 1200 | 2880 | 1200 | 12:5 | |
| 3440 x 1440 | 3440 | 1440 | 43:18 | WQHD |
| 3840 x 1600 | 3840 | 1600 | 12:5 | |
| 4320 x 1800 | 4320 | 1800 | 12:5 | |
| 5120 x 2160 | 5120 | 2160 | 64:27 | WUHD+ |
| 5160 x 2160 | 5160 | 2160 | 43:18 | WUHD+ |
| 5760 x 2400 | 5760 | 2400 | 12:5 | |
| 6880 x 2880 | 6880 | 2880 | 43:18 | |
| 7680 x 3240 | 7680 | 3240 | 64:27 | |
| 7680 x 3200 | 7680 | 3200 | 12:5 | |
| 8640 x 3600 | 8640 | 3600 | 12:5 | |
| 10240 x 4320 | 10240 | 4320 | 43:18 | 8K WUHD+ |
Common 21:9 screen sizes
Here are the width, height, and diagonal of various 21:9 image, video, or screen sizes in inches and centimeters.
| Diagonal | Width | Height |
|---|---|---|
| 1″ 2.54 cm | 0.92″ 2.33 cm | 0.39″ 1 cm |
| 2″ 5.08 cm | 1.84″ 4.67 cm | 0.79″ 2 cm |
| 3″ 7.62 cm | 2.76″ 7 cm | 1.18″ 3 cm |
| 4″ 10.16 cm | 3.68″ 9.34 cm | 1.58″ 4 cm |
| 5″ 12.7 cm | 4.6″ 11.67 cm | 1.97″ 5 cm |
| 6″ 15.24 cm | 5.51″ 14.01 cm | 2.36″ 6 cm |
| 7″ 17.78 cm | 6.43″ 16.34 cm | 2.76″ 7 cm |
| 8″ 20.32 cm | 7.35″ 18.68 cm | 3.15″ 8 cm |
| 9″ 22.86 cm | 8.27″ 21.01 cm | 3.55″ 9 cm |
| 10″ 25.4 cm | 9.19″ 23.35 cm | 3.94″ 10.01 cm |
| 11″ 27.94 cm | 10.11″ 25.68 cm | 4.33″ 11.01 cm |
| 12″ 30.48 cm | 11.03″ 28.02 cm | 4.73″ 12.01 cm |
| 13″ 33.02 cm | 11.95″ 30.35 cm | 5.12″ 13.01 cm |
| 14″ 35.56 cm | 12.87″ 32.68 cm | 5.51″ 14.01 cm |
| 15″ 38.1 cm | 13.79″ 35.02 cm | 5.91″ 15.01 cm |
| 16″ 40.64 cm | 14.71″ 37.35 cm | 6.3″ 16.01 cm |
| 17″ 43.18 cm | 15.63″ 39.69 cm | 6.7″ 17.01 cm |
| 18″ 45.72 cm | 16.54″ 42.02 cm | 7.09″ 18.01 cm |
| 19″ 48.26 cm | 17.46″ 44.36 cm | 7.48″ 19.01 cm |
| 20″ 50.8 cm | 18.38″ 46.69 cm | 7.88″ 20.01 cm |
| 21″ 53.34 cm | 19.3″ 49.03 cm | 8.27″ 21.01 cm |
| 22″ 55.88 cm | 20.22″ 51.36 cm | 8.67″ 22.01 cm |
| 23″ 58.42 cm | 21.14″ 53.7 cm | 9.06″ 23.01 cm |
| 24″ 60.96 cm | 22.06″ 56.03 cm | 9.45″ 24.01 cm |
| 25″ 63.5 cm | 22.98″ 58.37 cm | 9.85″ 25.01 cm |
| 26″ 66.04 cm | 23.9″ 60.7 cm | 10.24″ 26.01 cm |
| 27″ 68.58 cm | 24.82″ 63.03 cm | 10.64″ 27.01 cm |
| 28″ 71.12 cm | 25.74″ 65.37 cm | 11.03″ 28.02 cm |
| 29″ 73.66 cm | 26.66″ 67.7 cm | 11.42″ 29.02 cm |
| 30″ 76.2 cm | 27.57″ 70.04 cm | 11.82″ 30.02 cm |
| 32″ 81.28 cm | 29.41″ 74.71 cm | 12.61″ 32.02 cm |
| 34″ 86.36 cm | 31.25″ 79.38 cm | 13.39″ 34.02 cm |
| 40″ 101.6 cm | 36.77″ 93.39 cm | 15.76″ 40.02 cm |
| 42″ 106.68 cm | 38.6″ 98.05 cm | 16.54″ 42.02 cm |
| 43″ 109.22 cm | 39.52″ 100.39 cm | 16.94″ 43.02 cm |
| 48″ 121.92 cm | 44.12″ 112.06 cm | 18.91″ 48.03 cm |
| 50″ 127 cm | 45.96″ 116.73 cm | 19.7″ 50.03 cm |
| 55″ 139.7 cm | 50.55″ 128.4 cm | 21.67″ 55.03 cm |
| 58″ 147.32 cm | 53.31″ 135.41 cm | 22.85″ 58.03 cm |
| 60″ 152.4 cm | 55.15″ 140.08 cm | 23.64″ 60.03 cm |
| 65″ 165.1 cm | 59.74″ 151.75 cm | 25.6″ 65.04 cm |
| 70″ 177.8 cm | 64.34″ 163.42 cm | 27.57″ 70.04 cm |
| 75″ 190.5 cm | 68.94″ 175.1 cm | 29.54″ 75.04 cm |
| 77″ 195.58 cm | 70.77″ 179.77 cm | 30.33″ 77.04 cm |
| 83″ 210.82 cm | 76.29″ 193.77 cm | 32.7″ 83.05 cm |
| 85″ 215.9 cm | 78.13″ 198.44 cm | 33.48″ 85.05 cm |
| 86″ 218.44 cm | 79.05″ 200.78 cm | 33.88″ 86.05 cm |
| 97″ 246.38 cm | 89.16″ 226.46 cm | 38.21″ 97.05 cm |
| 98″ 248.92 cm | 90.08″ 228.79 cm | 38.6″ 98.05 cm |
FAQs
How do I calculate the 21:9 aspect ratio?
The 21:9 aspect ratio is an ultrawide screen or image format that proportionally contains twenty-one units horizontally for every nine vertically. It can be calculated by dividing the width by height and getting a value of 2.33 (2.333334).
For example, the ratio between the width and height of the Ultrawide HD (1680 x 720), Ultrawide Full HD (2520 x 1080), and Ultrawide 4K UHD+ (5040 x 2160) resolutions are equal to 2.33.
