How to rotate a video
- Drop an MP4, MOV, M4V, WebM or MKV into the box above. The line under the preview shows its size, length and resolution, and whether it is already stored on its side with a rotation note (most vertical phone videos are).
- Press 90° left, 90° right or 180° until the preview stands the right way up. Press Flip left–right or Flip upside down to mirror it.
- Leave Keep quality selected unless you have a reason not to (see below), and press Rotate video.
- Check the result in the player, read What came out, and download.
Rotating without re-encoding, and how we know it works
An MP4 or MOV file stores, next to the video itself, a small grid of numbers that tells the player how to turn the picture before showing it. Phones use it all the time: the camera records with the sensor on its side and writes “turn this 90°” into the file. Changing that note turns the video without decoding a single frame, so it takes a fraction of a second and the picture is exactly what it was.
Most online rotators do not do this. They decode the whole video, turn every frame and encode it again, which is slower and costs a little quality each time. To check our approach, we made a test clip with four coloured quarters (red, green, blue, white) and ran it through every setting:
| Setting | Frames identical to the original | Chrome shows | Windows File Explorer thumbnail |
|---|---|---|---|
| 90° right | 60 of 60 | turned, correct | turned, correct |
| 180° | 60 of 60 | turned, correct | turned, correct |
| 90° left | 60 of 60 | turned, correct | turned, correct |
| Mirror, as a note in the file | 60 of 60 | mirrored, correct | not mirrored |
The last row is why this page never mirrors with a note. Chrome obeyed it, but Windows showed the clip unmirrored, which would make a mirrored selfie video look fine on one screen and backwards on another. So mirroring always rebuilds the picture, and the page tells you so before you start.
On a real 12-second vertical phone video (1080×1920, 12.16 MB), turning it 90° left took 0.06 seconds and all 360 frames came out byte-for-byte identical. The file size did not change at all.
When to choose “Turn the pixels”
The rotation note is part of the MP4 format; Chrome and Windows read it in our test, and phones write it themselves. Software that ignores it does exist, typically older video editors and media players. If your rotated video still shows on its side there, run it again with Turn the pixels. The picture is then decoded, turned and encoded as H.264 at about the original bitrate, and the note is reset, so every program shows the same thing. On the test clip the colours of all four quarters matched the original exactly as Chrome displayed them.
WebM and MKV files cannot hold a rotation note at all, so they always take this route and come out as MP4. A screen recording from a browser is usually a WebM; if you only need it as MP4 without turning it, WebM to MP4 keeps every frame of those recordings.
Why your video is sideways in the first place
If a phone video is sideways on your computer but upright on the phone, the file is usually fine and the program you opened it with is ignoring the rotation note. If it is sideways everywhere, the phone was held at an angle when recording started and wrote the wrong note, which happens when the phone is flat on a table. Either way, one quarter turn here fixes it without touching the picture.
Related tools
- Crop video — cut the picture down to a square, 9:16 or 4:5 frame.
- Trim video — cut the start or end off, also without re-encoding.
- Compress video — make the file fit an upload limit.
- Rotate image — the same for photos.