Video Rotator
Fix a sideways MP4 or MOV video without re-encoding. Free, no upload.
How It Works
Select a video. The tool reads the file's header and shows the rotation it currently carries. Pick how far to turn it and click Rotate Video. The new rotation is added to the old one, so a video flagged 90° and turned another 90° clockwise ends up at 180°. Preview the result, then download it. Nothing is uploaded.
Only the rotation setting changes. The video and audio data are copied byte for byte, so the result is ready instantly and is exactly the same quality as the original.
Not sure why the video came out sideways? Read why videos end up sideways and how to fix them.
The Rotation Flag, Explained
MP4 and MOV files are built from labelled sections. Each track has a header (tkhd) containing a 3×3 transformation matrix that tells the player how to place the picture on screen. Phones record with the sensor in its natural landscape position and write a 90°, 180° or 270° matrix depending on how the phone was held, instead of turning every frame. Apple's camera framework describes this approach: the rotation goes into the file's metadata and video players apply it during playback.
When a phone guesses wrong, typically because recording started with the phone lying flat, the flag is wrong and the video plays sideways. Changing the flag fixes it without touching a single frame.
Limits
- MP4, MOV and M4V only. WebM, MKV and AVI files are rejected.
- Players that ignore the rotation flag (some older players, TVs and editing programs) still show the video as it was stored. For those, re-encode it in a video editor.
- Turns in 90° steps only. It can't straighten a slightly tilted video, crop it or mirror it.
- Videos with an unusual existing transform (mirrored or scaled) are left alone.
| Flag | Stored | Shown as |
|---|---|---|
| 0° | 1920 × 1080 | 1920 × 1080 (landscape) |
| 90° | 1920 × 1080 | 1080 × 1920 (portrait) |
| 180° | 1920 × 1080 | 1920 × 1080 (upside down) |
| 270° | 1920 × 1080 | 1080 × 1920 (portrait) |
Frequently Asked Questions
Does rotating a video here reduce its quality?
No. MP4 and MOV files carry a small rotation setting in the video track's header that tells players which way to turn the picture. This tool changes only that setting (36 bytes) and copies the video and audio data unchanged, so quality and file size stay the same.
Why does my video still look sideways in some players after rotating?
The rotation is a flag that the player has to apply. Phones, current web browsers and most modern players honour it, but some older players, TVs and video editors ignore it and show the stored picture as it was recorded. If the video must look right everywhere, re-encode it with a video editor so the pixels themselves are turned.
Which formats are supported?
MP4, MOV and M4V files, which covers videos recorded on iPhones and almost all Android phones. WebM, MKV and AVI files are not supported: they don't use the same rotation setting.
How large a video can I rotate?
Large ones. The tool reads only the small header section of the file into memory and reuses the rest of the original file as it is, so even multi-gigabyte phone videos are processed in a moment.
Why does it show a rotation for a video that looks fine?
Phones usually record with the camera sensor in landscape and set a rotation flag for portrait videos. An upright portrait iPhone video is typically stored as 1920 × 1080 with a 90° flag, which players show as 1080 × 1920.
Is my video uploaded?
No. The file is read and the new copy is made by JavaScript in this page. Nothing is sent to a server.