Why phone videos end up sideways
Phones don't physically rotate the camera sensor when you turn them. They record every frame the same way round and store a rotation instruction in the file (in MP4 and MOV, a 'display matrix') saying how to turn the picture for playback. Most players read it. Some don't, including older Windows apps, some TVs and media players, certain web upload pipelines and some editing tools, and they show the video sideways.
The other common case is a phone that guessed the orientation wrong, usually because it was lying flat when recording started. Then even well-behaved players show it sideways, because the stored instruction itself is wrong.
How this tool fixes it for good
This tool applies the rotation to the pixels themselves. The video is decoded, every frame is turned (or mirrored), and the result is encoded as a fresh H.264 MP4 at high quality (CRF 23). The output has no rotation flag to be misread: it's simply upright, so it plays correctly in every player, editor and upload form.
Any existing rotation flag is applied first, so you choose the rotation relative to how the video currently looks in your browser's preview, which is how it appears on most devices.
Which rotation option do I need?
Look at the preview and pick the option that matches what you see:
- 90° right: the top of the picture is on the left side and should be at the top (the picture needs turning clockwise).
- 90° left: the top of the picture is on the right side (turn it anticlockwise).
- 180°: upside down, common when a phone was held the 'wrong' way up in landscape.
- Flip horizontal: a mirror image, typical of selfie videos where text appears backwards.
- Flip vertical: mirrored top to bottom, which some webcam, scanner and microscope software produce.
Does rotating change the video's shape?
A 90° rotation swaps width and height: a 1920×1080 landscape video becomes 1080×1920 portrait, and vice versa. That's usually exactly what you want when fixing a sideways video. If you need it in a specific frame shape afterwards, such as square for Instagram, run it through Crop Video.
180° and flips keep the original dimensions.
Sound, quality and privacy
The audio is copied as-is when it's AAC and converted to AAC otherwise, and stays in sync. Because every frame is re-encoded, rotation takes about as long as the video plays on a laptop, longer on a phone, and it uses a high-quality setting so the difference from the original is hard to see.
The work happens in your browser with ffmpeg. The video isn't uploaded anywhere and nothing is added to it. That matters for family videos, which are the ones most often recorded sideways.
Can I rotate a video on my phone instead?
If the video plays sideways only on your own phone, the phone's editor can fix it: in iPhone Photos, open the video, tap Edit, then the crop icon, and use the rotate button; in Google Photos on Android, tap Edit, then Crop, then Rotate. On Windows, the Clipchamp editor that comes with Windows 11 can rotate and export a clip.
Use this tool when the video is already on a computer without an editor, when it needs to play correctly in an app or player that ignores rotation flags, or when you need a mirror flip, which most phone editors don't offer for video.