The 21:9 aspect ratio means 21 units wide for every 9 units tall (a decimal ratio of 2.33:1). Below are the exact 21:9 pixel sizes, a full dimensions table, and a free calculator to convert any 21:9 ratio to width × height.
21:9 is an aspect ratio, not a fixed pixel size — any width and height that divide to 2.33 is 21:9. The most common 21:9 size is 3440 × 1440 px. To get exact pixels, use the calculator below, or multiply your chosen width by 9/21 to get the height.
| Use | Pixels (W × H) |
|---|---|
| Ultrawide wallpaper | 3440 × 1440 |
| Cinematic banner | 2560 × 1080 |
Every row below is a perfect 21:9 ratio. Pick the resolution you need, or enter your own numbers in the calculator.
| Tier | Width | Height | Pixels |
|---|---|---|---|
| HD | 840 | 360 | 840 × 360 |
| Full HD | 1120 | 480 | 1120 × 480 |
| Full HD | 1680 | 720 | 1680 × 720 |
| QHD+ | 2520 | 1080 | 2520 × 1080 |
| QHD+ | 3360 | 1440 | 3360 × 1440 |
| 4K | 5040 | 2160 | 5040 × 2160 |
Convert a ratio to pixels, pixels to a ratio, or resize while keeping 21:9 locked.
Common sizes for 9:16
Need to crop an image to 21:9?
Use the free 21:9 crop tool — it locks the crop box to 21:9 so the proportions are always exact.
21:9 is a ratio, not a single size — any width and height that divide to 2.33 is 21:9. The most common 21:9 pixel size is 3440 × 1440. To get exact pixels, pick a width and multiply by 9/21 for the height (or use the calculator on this page).
21:9 means the width is 21 units for every 9 units of height (a decimal ratio of 2.33:1). Popular 21:9 sizes are 3440 × 1440, 2560 × 1080.
Enter any width in the calculator above and it returns the exact 21:9 height instantly (height = width × 9 ÷ 21), or enter a height to get the width. It also works in reverse: paste any pixel size and it tells you the ratio.
No. 21:9 and 9:21 use the same numbers but swapped, so one is landscape and the other portrait. 21:9 is wider than it is tall; 9:21 is the portrait version.
Use the free SammaPix crop tool: open it, choose the 21:9 preset, drag the box over the area to keep, and download. It locks to 21:9 so the proportions are always exact, and it runs 100% in your browser.
16:9 in pixels
The widescreen standard — perfect for YouTube thumbnails and videos (1280×720, 1920×1080), presentation slides, desktop wallpapers, and any 16:9 display or player.
2:1 in pixels
The wide banner format — perfect for X (Twitter) summary card images, website header banners, and panoramic compositions (commonly 1200×600 px).
4:3 in pixels
The classic standard — perfect for traditional photography, iPad and tablet screens, older monitors and TVs, and many presentation templates.
1:1 in pixels
The classic square — perfect for Instagram feed posts, profile pictures and avatars, album covers, and product thumbnails that display as a square.