You shot a great video, posted it, and it looks wrong. Black bars on the sides, a face cut off at the top, or text hidden behind the buttons. The cause is almost always the video size.
Each platform shows video in a certain shape. If your shape does not match, the app crops it, stretches it or adds bars. This guide gives you the sizes that work and a simple way to fix a video that does not fit.
The short version
For Reels, TikTok and YouTube Shorts, use 9:16 vertical video at 1080 x 1920. Fix any video for free with the Resize & Crop Video tool.
What is an aspect ratio?
The aspect ratio is the shape of the video: its width compared to its height. A phone held upright is tall and narrow, written as 9:16. A TV or laptop is wide, written as 16:9. A square is 1:1.
The best size for each platform
| Where | Best shape | Size in pixels |
|---|---|---|
| Instagram Reels | 9:16 vertical | 1080 x 1920 |
| TikTok | 9:16 vertical | 1080 x 1920 |
| YouTube Shorts | 9:16 vertical | 1080 x 1920 |
| Instagram feed post | 4:5 or 1:1 | 1080 x 1350 or 1080 x 1080 |
| YouTube (normal video) | 16:9 wide | 1920 x 1080 |
Platform rules change from time to time, so check the app if you are unsure. But 9:16 at 1080 x 1920 has stayed the standard for short vertical video.
Why vertical wins on phones
Most people watch short videos on a phone held upright. A 9:16 video fills the whole screen, so there are no bars and the picture looks bigger. Wide videos shrink into a small strip in the middle of the screen.
How to resize a video for free
- Open the free Resize & Crop Video tool.
- Drop your video in.
- Pick a shape: 9:16, 1:1, 4:5 or 16:9.
- Slide the crop to frame the person or the action.
- Press Resize and download.
You have two choices when the shape does not match:
- Fill the frame trims the edges so the picture covers everything. No bars, but you lose some of the sides.
- Fit inside keeps the whole picture and adds black bars.
The tool never makes the picture bigger than it already is, so quality is not wasted.
Protect your captions: the safe zone
Even at the right size, the app covers part of the screen with buttons, the username and the caption text. If your captions sit there, people cannot read them. Keep them in the safe zone: away from the very top, the bottom and the right edge. Our guide on the caption safe zone for Reels, TikTok and Shorts shows exactly where.
CapsField has a safe zone guide built into the editor. Try it on your own video, and see it before you export.
A quick checklist before you post
- The video is 9:16 and about 1080 x 1920.
- The speaker’s face is not too close to the top or bottom edge.
- The file is not huge. If it is, use the free Video Compressor.
- Captions are on and inside the safe zone.
- The first two seconds are strong, because that is when people decide to stay.
Common questions
Can I post a wide video on Reels?
You can, but it shows small in the middle of the screen with bars above and below. Resize it to 9:16 for a better result.
Is 4:5 better than 1:1 for the feed?
4:5 takes more screen space than a square, so it usually looks bigger in the feed.
Will resizing lower the quality?
Cropping does not blur the picture. The tool will not enlarge a video past its original size, so there is no stretch blur.
What about the file format?
MP4 is the safest. If you have a MOV file, see how to convert MOV to MP4 for free.
Resize, then caption
A correctly sized video with clear captions gets watched longer. Create a free CapsField account and add Urdu, Hindi, Hinglish, Punjabi or English captions in minutes. Need other quick fixes? Browse the free video tools.
