21:9 aspect ratio
2.3333:1 · 2560×1097 px · also called 2.33:1, cinematic wide, ultrawide
21:9 (properly 2.333:1) is the ultrawide monitor and cinematic-banner ratio. In advertising it shows up as desktop hero art and site-wide takeovers rather than in-feed placements.
What 21:9 means
A 21:9 frame is 2.333 times wider than it is tall. Multiply the width by 9/21 (0.4286) to get the height. Common sizes: 2560×1080, 3440×1440, 5120×2160.
Where it is used
Desktop website heroes, ultrawide display advertising, cinematic brand films and CTV bumper art.
21:9 in pixels
Every row below is exactly 21:9. Divide the width by 2.3333 to get the height for any size not listed.
| Width (px) | Height (px) | Total pixels |
|---|---|---|
| 1280 | 549 | 0.70 MP |
| 1720 | 737 | 1.27 MP |
| 2560 | 1097 | 2.81 MP |
| 3440 | 1474 | 5.07 MP |
| 5120 | 2194 | 11.23 MP |
21:9 in mm and inches
Physical equivalents at common print widths, with the pixel size needed for 300 DPI print.
| Width (mm) | Height (mm) | Inches | Pixels @ 300 DPI |
|---|---|---|---|
| 50 | 21.4 | 1.97″ × 0.84″ | 591×253 |
| 100 | 42.9 | 3.94″ × 1.69″ | 1181×507 |
| 150 | 64.3 | 5.91″ × 2.53″ | 1772×759 |
| 210 | 90 | 8.27″ × 3.54″ | 2480×1063 |
| 297 | 127.3 | 11.69″ × 5.01″ | 3508×1504 |
Working with 21:9
- 01Design a centred 16:9 core so the same art can be cropped for mobile without losing the subject.
- 02Avoid text in the outer 15% — responsive heroes crop the sides first.
- 03Serve a 4:5 mobile variant; never scale a 21:9 hero down for phones.
21:9 questions, answered
What is 21:9 in pixels?
2560×1080 px and 3440×1440 px are the standard ultrawide resolutions.
Is 21:9 exactly 21 by 9?
No — 2560×1080 is 2.370:1 and 3440×1440 is 2.389:1. '21:9' is marketing shorthand for roughly 2.33:1.
Can I run 21:9 ads on Meta?
No. Meta caps landscape at 1.91:1; wider assets get letterboxed or rejected.
Free tools for 21:9
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