How to Rotate a Video for YouTube
If you need to rotate a video for YouTube, the fix has to happen in the file before you upload it, and it has to change the pixels, not just a flag attached to them. That distinction is why so many "rotated" clips still land sideways.
Rotate a video for YouTube before it goes up
Studio's Editor gives you trimming, blurring, audio and end screens. Orientation isn't in that list, and aspect ratio is settled at upload, so a sideways video means re-encoding and uploading again, with a new URL, and none of the views or comments the original had.
The practical order is: rotate in an editor, export a new file, watch the first two seconds of that exported file in a player you didn't edit in, then upload.
Why the rotation didn't stick the first time
Phones frequently record a clip in one orientation and attach a rotation instruction rather than storing the picture the right way up. Your phone's player reads the instruction. Plenty of other software doesn't.
YouTube's recommended upload settings point straight at this. They ask for an MP4 container with no Edit Lists and the moov atom at the front of the file , the setting usually labelled Fast Start , with video encoded as H.264 using progressive scan rather than interlacing. Edit lists are precisely the mechanism a rotation flag rides in on. A file that follows the spec has no room left to carry a contradictory instruction about which way is up.
An export that checks its own dimensions
Orientation bugs are silent. Nothing warns you; the file just plays wrong somewhere else.
Montaj doesn't have a rotate control — it won't turn a clip 90 degrees. What it does do is verify each export before declaring it finished, checking the duration, the dimensions, the audio, and decoding frames to confirm the file is real. For the failure this page is about, that dimensions check is the useful one: the file that comes out is measured, not assumed. Confirm the frame there, and you won't have to rotate a video for YouTube twice.
How to fix a sideways YouTube upload in 4 steps
- 1
Work out whether the pixels are rotated or just the metadata
A clip can play upright everywhere on your phone and still upload sideways, because the rotation lives in a metadata flag your player honours and the encoder doesn't.
- 2
Re-encode so the rotation is baked into the picture
Rotating in an editor and exporting produces a file whose pixels are actually the right way up, rather than a file carrying an instruction to turn them.
- 3
Follow YouTube's container guidance
YouTube's recommended upload settings ask for an MP4 container with no Edit Lists and the moov atom at the front of the file, known as Fast Start. Edit lists are exactly where a stray rotation instruction tends to hide.
- 4
Check the frame before uploading, not after
Aspect ratio is fixed at upload and Studio's Editor has no rotate control, so a sideways upload means re-uploading and losing the URL, views and comments.
The verdict
— Kenji, Content Creator & Strategist