21:9 aspect ratio (2.333:1): resolutions and sizes
21:9 means 21 units wide for every 9 tall, so width ÷ height = 2.333 and the height is 42.9% of the width. 21:9 reduces to 7:3. Exact 21:9 sizes are whole multiples of 7 × 3, such as 2520 × 1080 (360 × 7 by 360 × 3).
Published · Updated · Sources last verified
At a glance
21:9
21:9 is 2.333:1, and reduces to 7:3.
- Decimal
- 2.333:1
- Reduced form
- 7:3
- Height as share of width
- 42.9%
- Exact sizes
- width a multiple of 7, height the same multiple of 3
21:9 widths at common heights
| Height | Width at 21:9 | Whole pixels | Size page |
|---|---|---|---|
| 360 | 840 | yes | - |
| 480 | 1120 | yes | - |
| 720 | 1680 | yes | - |
| 768 | 1792 | yes | - |
| 900 | 2100 | yes | - |
| 1080example size | 2520 | yes | - |
| 1200 | 2800 | yes | - |
| 1440 | 3360 | yes | - |
| 1600 | 3733.33 (nearest whole: 3733 × 1600) | no | - |
| 2160 | 5040 | yes | - |
Crop common sizes to 21:9
| Size | Centered 21:9 crop | Share kept | Exact |
|---|---|---|---|
| 1920 × 1080 | 1920 × 823 | 76.2% | no |
| 3440 × 1440 | 3360 × 1440 | 97.7% | yes |
| 1080 × 1920 | 1080 × 463 | 24.1% | no |
| 2560 × 1440 | 2560 × 1097 | 76.2% | no |
| 1280 × 720 | 1280 × 549 | 76.3% | no |
| 3840 × 2160 | 3840 × 1646 | 76.2% | no |
| 1080 × 1350 | 1080 × 463 | 34.3% | no |
| 1920 × 1200 | 1920 × 823 | 68.6% | no |
21:9 against other ratios
| Other ratio | Decimal | Share kept or filled | Cropping 21:9 cuts | Padding adds bars |
|---|---|---|---|---|
| 16:9 | 1.778:1 | 76.2% | the sides | top and bottom |
| 9:16 | 1:1.778 | 24.1% | the sides | top and bottom |
| 4:5 | 1:1.25 | 34.3% | the sides | top and bottom |
| 1:1 | 1:1 | 42.9% | the sides | top and bottom |
| 4:3 | 1.333:1 | 57.1% | the sides | top and bottom |
| 1.91:1 | 1.91:1 | 81.9% | the sides | top and bottom |
Sizes close to 21:9
None of our 24 resolution pages is exactly 21:9; the sizes table above lists exact ones. These pages come close:
Facts about 21:9
- The smallest whole-pixel 21:9 size is 7 × 3; 9 of the 10 common heights in the table give a whole-pixel width.
- No whole-pixel 21:9 size is 1600 px tall: the width would be 3733.33 px.
- 2560 × 1080 and 3440 × 1440 are close to 21:9 but not on it: 1.59% and 2.38% off.
- Cropping 21:9 to 9:16 keeps the least of the common ratios, 24.1%; cropping to 1.91:1 keeps the most, 81.9%.
- Of the listed sizes in the crop table, 3440 × 1440 keeps the most when cropped to 21:9 (97.7%) and 1080 × 1920 the least (24.1%).
Sourced notes
"21:9" is a marketing name. Wikipedia files the TVs sold as 21:9 cinema displays from 2009 to 2012 under 64:27, which is wider than an exact 21:9 (7:3).
Source: Wikipedia: Aspect ratio (image). Last verified 2026-10-05.
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Aspect ratio 7:3 (2.333:1). Exact match for 21:9.
Aspect ratio
7:3
2.333:1
Exact match for 21:9.
- Width ÷ height
- 2.3333
- Height ÷ width
- 0.4286
- Shape
- landscape
Your numbers, worked
gcd(2520, 1080) = 360
2520 ÷ 360 = 7
1080 ÷ 360 = 3
2520 ÷ 1080 = 2.3333
Show how the gcd was found
- 2520 = 2 × 1080 + 360
- 1080 = 3 × 360 + 0
Divide the larger side by the smaller, then divide the last divisor by the remainder until the remainder is 0. The last divisor is the gcd.
What each ratio would cut from 2520 × 1080
The largest centred crop at each ratio, best fit first. Crop rather than stretch.
| Ratio | Fit | Crop to | Lost |
|---|---|---|---|
| 21:9 | Exact | 2520 × 1080 | 0% |
| 2:1 | Trim width | 2160 × 1080 | 14.3% |
| 1.91:1 | Trim width | 2063 × 1080 | 18.1% |
| 16:9 | Trim width | 1920 × 1080 | 23.8% |
| 16:10 | Trim width | 1728 × 1080 | 31.4% |
| 32:9 | Trim height | 2520 × 709 | 34.4% |
| 3:2 | Trim width | 1620 × 1080 | 35.7% |
| 4:3 | Trim width | 1440 × 1080 | 42.9% |
| 5:4 | Trim width | 1350 × 1080 | 46.4% |
| 1:1 | Trim width | 1080 × 1080 | 57.1% |
| 4:5 | Trim width | 864 × 1080 | 65.7% |
| 3:4 | Trim width | 810 × 1080 | 67.9% |
| 2:3 | Trim width | 720 × 1080 | 71.4% |
| 9:16 | Trim width | 608 × 1080 | 75.9% |
Solve the missing side
Pick a ratio, then enter the side you know.
Height is 1080. Size 2520 by 1080 pixels.
Size at 21:9
2520 × 1080
Height solved, in pixels.
Your numbers, worked
H = W × 9 ÷ 21 = 2520 × 9 ÷ 21 = 1080
Whole number, so no rounding is needed.
Pixel-exact: a 7:3 size needs the width to be a multiple of 7, and 2520 is 360 × 7.
Questions
What resolutions are 21:9?
1680 × 720, 1792 × 768, 2520 × 1080, 3360 × 1440 and 5040 × 2160 are exactly 21:9. Any size whose width is a multiple of 7 and whose height is the same multiple of 3 is exact. Not exact, though close: 2560 × 1080 (1.59% off) and 3440 × 1440 (2.38% off).
How do I work out a 21:9 height from a width?
Multiply the width by 3 and divide by 7: 2520 × 3 ÷ 7 = 1080. The other way, width = height × 7 ÷ 3. At 1600 px tall the width is 3733.33, so no exact whole-pixel 21:9 size is that tall.
How much of a 21:9 image does a 9:16 crop keep?
24.1%. The share kept is the smaller decimal divided by the larger: 0.563 ÷ 2.333. Padding a 21:9 image to 9:16 instead fills the same share of the canvas.
Nearby sizes
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Apart from the sourced notes above, which devices use this ratio, and marketing names for it, are not covered: we did not verify a primary source for them, so this page sticks to arithmetic.