Change a video’s aspect ratio without distorting it
Every platform has a favourite shape: 16:9 for YouTube and TVs, 9:16 for Reels, Shorts and TikTok, 1:1 and 4:5 for feed posts, 21:9 for a cinematic look. This video aspect ratio converter reshapes a clip to any of them in one of three ways — colour bars, a blurred background, or a crop you position yourself — and never squashes or stretches the people in it.
A preview shows the new frame straight away, so you can compare the three methods on your own footage before encoding. The output size follows the video’s short side by default (a 1920 × 1080 clip becomes 1080 × 1920 for 9:16), or you can choose 2160, 1440, 1080, 720, 480 or 360 pixels. Processing runs locally with WebCodecs and the Mediabunny library (MPL-2.0); nothing is uploaded.
How to use the Video Aspect Ratio Converter
- Drop your video on the upload area. Its current resolution is shown in the details panel.
- Choose the New aspect ratio: 16:9, 9:16, 1:1, 4:5, 4:3 or 21:9.
- Choose How to change the shape: Blurred background, Colour bars (pick the bar colour) or Crop. In crop mode, drag the preview to keep your subject in the frame.
- Leave “Output size” on Automatic or pick a fixed short side, such as 1080 px for social media.
- Press “Convert aspect ratio”, wait for the progress bar, compare Before and After, and download.
Video Aspect Ratio Converter features
Six common shapes
16:9, 9:16, 1:1, 4:5, 4:3 and 21:9 cover YouTube, Reels, Shorts, TikTok, feed posts, old TV footage and cinema framing.
Blurred background
Fills the empty space with a soft, darkened, zoomed copy of the video — the popular way to post landscape clips vertically.
Bars in any colour
Classic black letterbox or pillarbox bars, or white and brand colours for slides and promos.
Crop with a draggable focus
Fill the new frame completely and drag the preview to choose which part of the picture stays.
Sensible output sizes
Automatic keeps the short side of your clip; fixed sizes from 360 to 2160 px give exact social-media dimensions.
Private processing
Decoding and encoding happen in your browser — the video is never uploaded.
Aspect ratios and where they are used
The ratio describes shape, not size: a 9:16 video can be 720 × 1280 or 1080 × 1920. Work out sizes for any ratio with the aspect ratio calculator.
| Ratio | Example size | Where it is used |
|---|---|---|
| 16:9 | 1920 × 1080 | YouTube, TVs, laptops, presentations |
| 9:16 | 1080 × 1920 | Instagram Reels and Stories, YouTube Shorts, TikTok |
| 1:1 | 1080 × 1080 | Square feed posts and ads |
| 4:5 | 1080 × 1350 | Portrait feed posts on Instagram and Facebook |
| 4:3 | 1440 × 1080 | Older TV and camcorder footage, iPads, some webcams |
| 21:9 | 2520 × 1080 | Ultra-wide monitors and a cinematic letterboxed look |
Bars, blur or crop?
- Blurred background keeps the entire picture and looks deliberate on phones. It is the usual choice for turning a landscape clip into a 9:16 Reel or Short.
- Colour bars also keep the entire picture. Black is standard for film; a solid brand colour leaves room for captions or a logo added later in an editor.
- Crop fills the frame edge to edge, so nothing looks boxed in, but it cuts the sides (or the top and bottom). Turning 16:9 into 9:16 keeps only about a third of the width — fine for one person talking, poor for a wide group shot.
Getting the best result
Convert from the highest-quality copy you have, because every encode loses a little detail. When making vertical video from landscape footage, check the preview at several points with the frame slider — a subject who moves across the frame may leave a fixed crop. For exact pixel cropping use Crop Video; to change only the pixel count and keep the shape, use the video resizer. A sideways phone clip should be fixed with Rotate Video before you change its shape.
Video Aspect Ratio Converter FAQ
How do I change a video from 16:9 to 9:16?
Drop the video, choose 9:16, then “Blurred background” to keep the whole picture or “Crop” to fill the screen. With Automatic size a 1920 × 1080 clip becomes 1080 × 1920. Press “Convert aspect ratio” and download.
Will changing the aspect ratio stretch my video?
No. Bars and blur shrink the picture to fit and fill the space around it; crop trims the edges. The picture is never squashed or stretched.
What aspect ratio should I use for Instagram?
Use 9:16 (1080 × 1920) for Reels and Stories, and 4:5 (1080 × 1350) or 1:1 (1080 × 1080) for feed posts. Choose a 1080 px short side to get these exact sizes.
Can I convert a vertical video to horizontal?
Yes. Choose 16:9; a blurred background fills the sides so the vertical clip sits in the middle of a landscape frame, which suits YouTube and TVs.
Why does the crop option make my video smaller?
A crop keeps only part of the original pixels. With Automatic size the output uses those pixels at their original resolution; choose a fixed output size to scale the result up or down.
Is the video uploaded anywhere?
No. The aspect ratio conversion runs inside your browser and the file stays on your device.