Change video aspect ratio

Fit a video into 9:16, 1:1, 4:5, 16:9 and the other shapes platforms ask for, with blurred sides, a colour, or a centre cut.

Drop your files here

.mp4, .mov, .mkv, .webm, .avi · up to 200 MB

Choose files

How to Change the ratio

1
Add your video
MP4, MOV, MKV, WebM or AVI, up to 200 MB and five minutes. A horizontal clip headed for a vertical feed is the usual case.
2
Pick the target ratio
9:16 for Reels, Shorts and TikTok, 1:1 or 4:5 for feed posts, 16:9 for YouTube. Then choose how the gap gets filled.
3
Click Change and download
The result is an MP4 at a standard size for that shape, 1080 × 1920 for 9:16 and so on, with the sound intact.

Three ways to fill the gap, and none of them stretch

A landscape video does not fit a vertical hole, so something has to give. Blur puts a scaled-up, blurred copy of the video behind the picture and centres the sharp version on top: nothing is lost, nothing is empty, and it reads as deliberate rather than accidental. That is why it is the default and why most Reels made from landscape footage look like that. Pad fills the sides with a flat colour, black unless you choose otherwise, which suits graphics and screen recordings where a blurred background would just look smeared. Crop keeps the frame full by cutting the sides off, best when the subject sits in the middle and the edges are expendable. What none of them do is squeeze the picture into the new shape: stretched faces are the one outcome everybody notices.

Why the output is a fixed size

Each ratio maps to the resolution platforms expect: 1080 × 1920 for 9:16, 1080 × 1080 for square, 1080 × 1350 for 4:5, 1920 × 1080 for 16:9, 1440 × 1080 for 4:3 and 2560 × 1080 for 21:9. Uploading at exactly these numbers avoids a second round of scaling on the platform's side, which is where soft, mushy-looking uploads usually come from. If your source is smaller or the file needs to stay light, the 720 option divides every one of those by one and a half.

Which shape to pick

9:16 is the full-screen vertical format for Reels, Shorts and TikTok. 4:5 is the tallest a post can be in the Instagram feed and takes up more screen than a square, which is why it outperforms 1:1 for reach; 1:1 remains the safest single shape when the same file goes to several places. 16:9 is the default for YouTube and for anything watched on a television or a monitor. 21:9 is cinematic and mostly a stylistic choice. If you are not sure, 9:16 for stories and reels, 4:5 for the feed.

This is not the same as cropping

Cropping removes part of the picture; changing the ratio keeps all of it and builds the rest of the frame around it. The exception is the crop method here, which does cut, but to a fixed target shape and size rather than to a box you drag. If you want to choose the area by hand, the crop tool is the one you want, and its result can come straight here afterwards.

Reframed on your own device

Decoding every frame, blurring or padding the backdrop, composing the frame in the ratio you picked and encoding the result all happen in this tab, with the video encoder your browser already has. No frame is uploaded, there is no account or queue, and closing the tab clears the clip.

Frequently asked questions

What is the difference between pad, crop and blur?

Pad fills the empty sides with a flat colour. Crop cuts the picture down until it fills the shape. Blur puts a blurred copy of the video behind the sharp one, so nothing is lost and nothing is empty.

Which should I use for Reels or Shorts?

Blur at 9:16. It keeps the whole picture, fills the screen, and is the look people are used to seeing from landscape footage. Crop only if the subject is centred and the edges do not matter.

Does this lose quality?

The video is re-encoded once, at a bitrate chosen for the target size, so it is one generation of compression. Uploading at the platform's own resolution usually gains you more than that costs, because the platform then does not rescale it again.

Why can this not be done without re-encoding?

Because the frame itself changes: new pixels are added or removed. Only orientation can be changed by rewriting a flag; anything that alters the picture has to be encoded.

What if my video is already the right shape?

The tool says so and stops rather than re-encoding for nothing. If you only need the file smaller, compressing is the tool for that.

Can I pick the colour of the bars?

Yes, when you choose pad. Black is the default because it disappears against most players and platform backgrounds.

Is the sound kept?

Yes, at 128 kbps AAC. On browsers without an AAC encoder it is saved as Opus and the page tells you, since such a file plays in Chrome, Firefox and Edge but not in QuickTime.