Rotate Video
Turn a sideways or upside-down phone video the right way up without re-encoding it: no quality lost, no watermark. Only the file's rotation flag changes, on this device; the video is never uploaded.
Works on the file's own header, so a 4 GB clip turns as fast as a 4 MB one.
Turn it
Open a video to begin.
Privacy: the video is read in your browser and never uploaded. The page reads the file's box headers and its index (the moov box) in small pieces, writes 36 new bytes, and builds the copy from slices of your original. Nothing is kept after you close the tab.
How to rotate a video
- Open the video. Tap Open a video or drop an MP4, MOV or M4V on the box. The page shows its size and the angle it is set to now.
- Turn it. Tap 90° right, 90° left or 180° until the preview stands the right way up. Reset to 0° removes any rotation and shows the picture as the camera's sensor recorded it.
- Save. Tap Save rotated video. Chrome and Edge on a computer ask where to save; other browsers download the file with -rotated added to its name.
- Check it. Before saving, the page reads the new file's header back and confirms the angle; the copy is exactly as many bytes as the original.
Why this does not lose quality
A phone's sensor always records the same way round. When you hold the phone upright, the camera does not turn the pixels; it writes a rotation matrix into the MP4 or MOV header, nine numbers in the video track's tkhd box, and players turn the picture as they show it. A video plays sideways when that flag is wrong, typically because the phone was flat on a table or pointing at the floor when recording started, so the orientation sensor guessed wrong.
This page rewrites those 36 bytes and copies everything else. For 90° right the matrix becomes 0 1 0 / −1 0 0 / h 0 1: a 1920 × 1080 clip then plays as 1080 × 1920. Online rotators that upload the file instead decode and re-compress every frame, which costs quality and time and is why they cap the file size. Here the work does not grow with the video: a ten-minute 30 fps clip has 18,000 frames and its index is typically a few hundred kilobytes, and that index is all the page reads closely.
What it cannot do
- It does not re-encode, so it cannot turn WebM, MKV or AVI files. Those formats have no rotation flag that players reliably honour; turning them needs re-encoding, which this tool does not do. It says so when you open one.
- It cannot flip, mirror or crop. Only quarter turns: 90°, 180°, 270°. It cannot straighten a slightly tilted horizon either.
- A few players ignore the flag. Phones, browsers, VLC and QuickTime honour it; some old players, smart TVs and some video editors show the picture as stored. For those, the rotation has to be baked into the pixels by re-encoding.
- It does not change the audio, the length, the frames or anything else in the file. A file whose index is missing (a recording that was cut off) cannot be fixed here.
- The preview is only as good as this browser. HEVC (H.265, the iPhone default) previews in Safari and on some other devices; where it does not, the page still rotates the file, because nothing is decoded, and shows an outline in place of the picture.
Questions
How do I rotate a video on iPhone without an app?
In Photos, open the video, tap Share, then Save to Files. Open this page in Safari, tap Open a video, choose Browse and pick the copy in Files (picking straight from the photo library can hand Safari a compressed copy). Tap 90° right or 90° left until the preview is upright, then Save rotated video. Safari puts the new file in Downloads in the Files app; from there Share, Save Video puts it back in Photos.
How do I rotate a video on Android?
Open this page in Chrome, tap Open a video and choose the clip from your gallery or Files. Turn it until the preview is upright and tap Save rotated video. The file lands in Downloads with -rotated added to its name, and Google Photos and the gallery app pick it up from there.
Can I rotate a video without losing quality?
Yes, for MP4 and MOV. The picture is not decoded or re-encoded at all: the tool changes the nine numbers of the rotation matrix and copies every other byte. The output is exactly as long as the input, and every frame and the audio are bit-for-bit the original.
Is it free, with no watermark and no size limit?
Yes. There is no sign-up, no watermark (the frames are never touched, so nothing could be stamped on them) and no upload, so no upload limit. The file is read in small pieces, so a several-gigabyte clip works as long as your device has room to save the copy. The only network traffic after the page loads is an anonymous page-view count and two fixed event names (a video was opened, a video was saved), never the file, its name or anything in it.
Why does my rotated video still play sideways in one app?
That app ignores the rotation flag. Phones, browsers, VLC and QuickTime honour it, but a few older players, smart TVs and some video editors show the stored picture as it was recorded. For those, the video has to be re-encoded with the rotation baked into the pixels, which this tool does not do.