21:9 Aspect Ratio Calculator Explained

By Last updated: July 03, 2023

21:9 Aspect Ratio Calculator

What is a 21:9 aspect ratio?

Common Aspect Ratios

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), and 12:5 (3840x1600)[1].

Example 1

LG 29WN600-W 29 inch 21:9 UltraWide Monitor

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

Samsung 34" QLED Ultra WQHD 21:9 Curved Monitor

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.

ResolutionWidthHeightReal Aspect RatioStandard
1680 x 720168072021:9WHD
1920 x 800192080012:5
2520 x 10802520108021:9WHD
2560 x 10802560108064:27WFHD+
2880 x 12002880120012:5
3440 x 14403440144043:18WQHD
3840 x 16003840160012:5
4320 x 18004320180012:5
5120 x 21605120216064:27WUHD+
5160 x 21605160216043:18WUHD+
5760 x 24005760240012:5
6880 x 28806880288043:18
7680 x 32407680324064:27
7680 x 32007680320012:5
8640 x 36008640360012:5
10240 x 432010240432043:188K WUHD+
Table 1: common resolutions of 21 by 9 content and display.

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.

DiagonalWidthHeight
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
Table 2: Diagonal, width, and height of different 21 by 9 screen sizes

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.

21:9 Aspect Ratio Calculator

21:9 Aspect Ratio Calculator App

About this app

Use our 21:9 aspect ratio calculator to help you accurately resize or scale images, video, or screen resolution to perfect 21 by 9 dimensions. You will also learn more about the aspect ratio, formula, and calculation examples.

App availability

You can use the calculator for free as a PWA web app online or install it locally on any modern operating system, including Android, iOS, Windows 11/10, and macOS.

21:9 Aspect Ratio Calculator QR
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App changelog

Version 1.1
  • Added screen diagonal parameter, allowing you to find pixel density in PPI and screen width and height in inches and centimeters.
  • Added screen sizing table showing width, height, and pixel density for screen sizes ranging from 1 inch to 98 inches in diagonal.
Version 1.0
  • Automatically calculate width or height when you change any of those values.
  • A summary of resolution information along with virtualized graphics.
  • Add scaling table - show you resolutions that scale well with the one you entered from 5% to 200%.
  • Basic customization features.

References

3 Sources

  1. ⬆️ Wikipedia Contributors. 21:9 aspect ratio. Wikipedia. Published December 13, 2023. Accessed January 13, 2024.

    https://en.wikipedia.org/wiki/21:9_aspect_ratio
  2. ⬆️ LG 29WN600-W 29 inch 21:9 UltraWide WFHD IPS HDR10 Monitor with FreeSync. Lg.com. Published 2018. Accessed January 13, 2024.

    https://www.lg.com/us/monitors/lg-29wn600-w-ultrawide-monitor
  3. ⬆️ 34" QLED Ultra WQHD 21:9 Curved Monitor with ThunderboltTM 3. Samsung ca. Published August 21, 2020. Accessed January 13, 2024.

    https://www.samsung.com/ca/monitors/ultra-wide/thunderbolt-tm-3-curved-monitor-with-21-9-wide-screen-34-inch-lc34j791wtnxza/