Common presets
Standard aspect ratios by platform
Standard video aspect ratios
These are the ratios you will meet in practice, with the resolutions most commonly used for each.
| Ratio | Orientation | Common resolutions | Typical use |
|---|---|---|---|
| 16:9 | Horizontal | 1920×1080, 3840×2160, 1280×720 | YouTube, TV, presentations |
| 9:16 | Vertical | 1080×1920, 720×1280 | TikTok, Reels, Shorts, Stories |
| 1:1 | Square | 1080×1080, 720×720 | Instagram feed, X posts |
| 4:5 | Vertical | 1080×1350 | Instagram feed, maximum height |
| 4:3 | Horizontal | 1440×1080, 640×480 | Older cameras, archive footage |
| 21:9 | Ultrawide | 2560×1080, 3440×1440 | Cinematic video, film |
What happens when the ratio does not match
Each platform handles a mismatched upload differently. This is what to expect.
| Platform | Preferred | If it does not match |
|---|---|---|
| TikTok | 9:16 | Letterboxed, black bars above and below the video |
| Instagram Reels | 9:16 | Cropped to fill the screen, the edges are cut off |
| Instagram feed | 4:5 | Forced crop at upload, you choose the visible area |
| YouTube | 16:9 | Pillarboxed, bars on the left and right |
| YouTube Shorts | 9:16 | Accepted up to 1:1, wider videos stay in the regular player |
| X / Twitter | 16:9 | Timeline preview is cropped, the full video plays on tap |
Worked examples
Your clip is 1440×1080, which simplifies to 4:3, and Reels wants 9:16. Cropping keeps a strip of only 607×1080 pixels, so anything near the left and right edges is lost. If the subject stays centered, crop. If not, pad the top and bottom and accept the bars.
You filmed in 4K at 3840×2160 for TikTok. Dividing both sides by 240 gives 16:9, so the video plays horizontally with large bars. The ratio decides how a platform treats your video, not the resolution: a 4K file behaves exactly like a 1080p file of the same shape.
A 1080×1080 square video uploads to YouTube without errors, but the player adds bars on both sides. Posted as a Short, the same file plays nearly full screen on phones, because Shorts accepts square video.
How to calculate aspect ratio by hand
Divide both dimensions by the largest number that fits into both. For 1920×1080 that number is 120, so 1920/120 = 16 and 1080/120 = 9, which gives 16:9. When the numbers are awkward, divide width by height instead: 1.78 means 16:9, 0.5625 means 9:16, and 0.8 means 4:5.
Frequently asked questions
What happens if I upload a 16:9 video to TikTok?
TikTok keeps the video but letterboxes it, filling the space above and below with black bars. It plays smaller in the feed, and captions can overlap the bars. If the framing allows it, crop to 9:16 before uploading.
What resolution should a 9:16 video be?
1080×1920 is the standard. Any size with the same proportions scales cleanly, such as 720×1280. Higher resolutions are downscaled by the platform on upload.
Is 4:5 or 1:1 better for the Instagram feed?
4:5 at 1080×1350 fills more of the screen in the feed, so it usually performs better. 1:1 is the safer choice when you reuse the same file on other platforms.
Does changing the aspect ratio reduce quality?
Cropping discards part of the frame, and every re-export adds one more encode. Start from the highest quality source you have and export once, directly at the target ratio and resolution.