Rotate Video
Turn a sideways clip upright. Nothing is uploaded, whatever the size.
No size limit: only the file's index is read, not the picture data.
- 100% freeNo account, no daily quota, no paid tier.
- Nothing is uploadedFiles are processed on your device and never reach a server.
- No catch on the outputNo watermark, no forced downscaling, no size cap.
- Updated in the openEvery fix and every new tool is written down on the changelog page.
What this tool does
Drop a video in and this page turns it upright. Most of the time it does that without touching a single pixel. An MP4 or MOV file carries a small 3x3 display matrix that tells the player how far to rotate the picture on playback, and a clip that plays sideways has usually lost that matrix somewhere in an edit or an export. Writing it back means rewriting 36 bytes: the matrix itself; the stored frame size next to it stays as it is. The video stream is copied across untouched, so the saved file is the same picture at the same quality as the one you started with.
Nothing is uploaded, and that counts for more here than anywhere else on this site. A three minute clip off a phone runs 200 to 400 MB, and every other rotation service wants that pushed up your home connection before it will even look at it. This page reads the file where it sits. It only needs the small index at the front or the back, the box called moov, usually a few hundred kilobytes. The picture data is never read into memory, only referenced, which is why there is no size limit here: a 2 GB recording costs the same as a 20 MB one.
How to use it
Drag the file onto the page, or click to pick one. The first thing you see is what the file says about its own orientation, either "No rotation flag in this file" or "Rotation flag: 90° clockwise". Online rotators do not normally show you this, and it is worth knowing first: it tells you whether the clip is sideways because a flag went missing or because the pixels really were recorded that way.
The two arrow buttons turn the picture a quarter turn each and the middle button flips it end over end. The preview is not an approximation. The player is playing the finished file, the same bytes you get when you press Save, and the playback position is kept when you turn, so you can park on a frame with a clear up and down and watch it land the right way. The saved file keeps its extension and takes the original name with -rotated added.
Under Output there are two ways of doing the job. Rotation flag is the default and works as described above. Re-encode decodes the video and writes the new orientation into the frames themselves, using the browser's WebCodecs interface so the encoding runs on your graphics hardware. It takes time in proportion to the length of the clip and it re-compresses the picture, which is why it is not the default.
When the flag is not enough
Rotation flags are read correctly by current browsers, by the photo apps on iOS and Android, and by YouTube, Instagram and TikTok when you upload. The places that still ignore them are older desktop players, a few third party Android players, and some editing software at import time, where a clip you just fixed can come into the timeline sideways again. If the video is headed somewhere like that, switch Output to Re-encode. WebM and MKV have no equivalent field at all, so those files always take the re-encode path and the page switches over and says why. Re-encoding needs WebCodecs, which Chrome, Edge and Safari 16.4 have; where it is missing, the flag method still works. If a file's matrix holds a scale or a mirror rather than a plain quarter turn, rewriting it would distort the picture, so the page leaves that file alone and offers re-encoding instead. Mirroring is not offered at all, because player support for a mirrored matrix is inconsistent enough that the result can look correct where you made it and wrong everywhere you send it.
Background: where the rotation flag comes from
A phone camera sensor is fixed to the body in one orientation and always reads out landscape. Hold the phone upright and nothing rotates the pixels; the camera writes a matrix into the file that says to turn the picture 90 degrees at playback. The mechanism is far older than the phone. It comes from Apple's QuickTime file format, whose 2001 specification became the basis of the first MP4 file format. MPEG-4 Part 14 followed as ISO/IEC 14496-14:2003, and the container was then generalised into the ISO base media file format, ISO/IEC 14496-12:2004. The track header box, tkhd, and its 3x3 matrix of 16.16 fixed point numbers came through all of that unchanged, which is why the same 36 bytes apply to a MOV written in 2003 and to an MP4 off a phone bought last week.
Where people use it
The everyday case is footage shot on a phone that arrives on a computer lying on its side, often after passing through a messaging app or an export that dropped the flag. Editors meet it when a clip enters a timeline rotated and they would rather fix the file once than add a transform to every cut. Dashcam and security camera exports are a category of their own, since those recorders mount the sensor whichever way fits the housing. If what you need is a still rather than the clip, take a screenshot and send it through crop image or rotate image; if there is a QR code in one of the frames, QR code reader will read it out of that screenshot. If it is only the sound you are after, video to MP3 lifts the audio track out without re-encoding it either.
Frequently asked questions
Does rotating a video lose quality?
Not on the default setting. The picture data is copied over byte for byte and only the orientation flag changes, so the saved file is identical to the original. The Re-encode option does re-compress, which is the reason it is not the default.
Is there a file size limit?
No. Only the small index at the front or back of the file is read, so a 2 GB recording is handled as quickly as a small one, and the file never leaves your computer.
My player still shows the video sideways after saving. Why?
That player is ignoring the rotation flag. Switch Output to Re-encode and save again, which writes the new orientation into the frames themselves so that nothing has to interpret a flag.
Can I rotate a WebM or MKV file?
Yes, but only through the Re-encode option. Those containers carry no rotation field to rewrite, so the frames have to be encoded again.
Can it mirror or flip a video horizontally?
No. A mirrored matrix is supported inconsistently across players, so a mirrored file can look correct in the player you checked it in and wrong in the next one.