Rotate Video

Fix a video that was filmed sideways or upside down, or mirror a selfie clip. MP4 and MOV files store a rotation flag that players apply when they show the video — the same flag phones write when you hold them upright. Changing that flag rotates the video instantly, at any file size, without touching the picture. For other formats, for flips, or for old players that ignore the flag, the video is re-encoded with the pixels turned. It all runs in your browser; nothing is uploaded.

How to use this tool

1. Choose one or more videos.
2. Pick the rotation or flip.
3. Keep "Instant" for MP4/MOV, or choose "Re-encode" if the video must look right in every editor and player.
4. Press Calculate and download the rotated video.

Formula

New flag = (current flag + rotation) mod 360°

The flag lives in the video track header (the tkhd matrix) and can only be 0°, 90°, 180° or 270°. A video already flagged 90° and rotated another 90° clockwise ends at 180°. Re-encoding applies the existing flag first and then turns the pixels (H.264, CRF 20), so the result is upright everywhere with no flag at all.

Example

A 1.8 GB iPhone clip that shows sideways, rotated 90° clockwise with the instant method, is ready in under a second at the same 1.8 GB. Re-encoding the same 3-minute 4K clip in a browser could take the better part of an hour.