Why Is My Video Sideways?

The Short Answer

Your phone doesn't turn the picture when you hold it upright. It records with the camera sensor in its usual position and writes a small rotation setting into the file, a note to the player that says "turn this 90 degrees".

A video plays sideways when that note is wrong, or when the app playing it ignores the note. A wrong note can be fixed in seconds, without re-encoding and without losing any quality.

How to Fix It

1. Check where it's sideways. Play the video on your phone and in a web browser. If it's sideways everywhere, the rotation setting is wrong; go to step 2. If it's only wrong in one app, TV or editor, that program ignores the setting; go to step 4.
2. Change the rotation setting. Open the Video Rotator, select the MP4 or MOV file, and see which rotation it currently has. Pick the turn that makes it upright (90° clockwise, 90° counter-clockwise or 180°) and click Rotate Video.
3. Check the preview, then download. Only the setting changes, so the download is ready instantly and is the same size and quality as the original.
4. If one player still shows it sideways, update or switch the player. Modern browsers, phones and most current players honour the setting. If you need the video to look right in a program that ignores it, re-encode it with a video editor so the pixels themselves are turned.

What the Rotation Setting Actually Is

MP4 and MOV files are made of labelled sections. Each track has a track header (tkhd) that holds a 3×3 transformation matrix. Apple's QuickTime File Format documentation explains that a transformation matrix maps points from one coordinate space into another, which is how it can rotate, scale or move the picture. A 90° matrix tells the player to turn the picture a quarter turn as it draws it.

Apple's camera documentation for app developers describes the same approach: rather than rotating every frame, an app can set the rotation on the file, which "alters the output file's metadata", and video players apply the rotation during playback.

So a portrait video is often stored as a landscape picture with a 90° flag. The Video Rotator shows this directly. A typical portrait phone video reads:

Things That Trip People Up

• Recording with the phone flat. Apple's camera framework works out which way is up from gravity. Pointing it straight down at a table, or up at a ceiling, leaves no clear "up", so the flag can be wrong. Hold the phone at an angle for a second before pressing record.
• Turning the phone mid-recording. A video track has one rotation setting for the whole clip. Starting in portrait and turning to landscape halfway doesn't switch it; the second half just looks sideways.
• Portrait Orientation Lock. This setting stops the screen from turning. Apple's camera framework takes the angle from gravity rather than from the screen, so the lock is not normally what makes a recording sideways.
• Uploading or converting. Some converters and older editing programs drop the rotation setting or ignore it. The result then looks sideways even though the original file was fine.
• WebM and MKV files. These formats don't use the MP4 rotation matrix, so the Video Rotator can't change them. Re-encoding is the only option there.

Platform Notes

iPhone: in the Photos app, open the video, tap Edit, tap the crop button, then tap the rotate button to turn it 90 degrees, and tap Done.

Android: in Google Photos, open the video, tap Edit, then Crop, then Rotate, and tap Save copy.

Mac: in QuickTime Player, choose View → Show Clips, select the clip, then choose rotate left or right from the Edit menu, and click Done.

Any computer: the Video Rotator works in the browser on Windows, Mac, Linux and phones, and changes only the rotation setting, so the result is identical in quality. It handles MP4, MOV and M4V.

Zoom or Discord: if the live camera view is sideways in a call, that's not about a file. In Zoom's desktop app the camera preview in the video settings has a rotate button that turns the picture 90 degrees per click.