Convexy

Convert MOV to MP4 on iPhone

Your iPhone records QuickTime MOV. Windows machines, upload forms, editors and websites want MP4. The two are closer than most people realise — and the conversion is less free than most guides admit.

MOV and MP4 are cousins, not strangers

Both are containers. Neither is a codec. A container is a box: it holds a video stream, an audio stream, timing information and metadata, and defines how they are laid out on disk.

MOV is Apple's QuickTime container. The MP4 specification was derived from it — ISO took QuickTime as the starting point for MPEG-4 Part 14. They share the same underlying atom/box structure. This is why the conversion is so often described as trivial.

Inside your iPhone's MOV, the video is almost always HEVC (H.265) if you shoot in "High Efficiency", or H.264 if you shoot in "Most Compatible". The audio is AAC. All of those are perfectly legal inside an MP4 as well. Nothing about the actual media needs to change.

The part most guides skip

Because the streams are compatible, a MOV can in principle be turned into an MP4 by remuxing — rewriting the container around the untouched video and audio, bit for bit, in seconds, with zero quality loss.

Convexy does not do that. It converts through Apple's video export pipeline, which re-encodes the video into the size and codec you pick. That means:

For the overwhelming majority of uses — sending a clip to a Windows user, uploading to a site, dropping it into a slide deck — this is fine, and the quality cost of one careful re-encode is not something you will see. But it is not free, and we would rather tell you than let you assume.

Choose "Original" quality to stay as close to the source as the pipeline allows. It is still a re-encode, but at the highest quality setting, and it will not throw away resolution you paid for.

Codec: the setting that actually decides compatibility

This matters more than the container, and it is where people get burned. Renaming a HEVC MOV to .mp4 gets you an MP4 that half your recipients still cannot play — because their problem was never the extension.

If you are converting because someone could not open your video, pick H.264. That is almost always the actual fix. The bigger file is the price of it working on the first try.

Quality and size

Convexy offers Low (480p), Medium (720p), High (1080p) and Original. There is also an Include audio toggle — turn it off and the audio track is dropped entirely, which is occasionally exactly what you want and, when it is not, is an unpleasant surprise. Check it before you convert.

The honest guidance: pick the resolution you actually need, not the one you have. A 4K clip going into a slide deck, a messaging app or a web page does not need to arrive at 4K, and downscaling to 1080p at H.264 will produce a far more manageable file than anything you get by fiddling with the container.

It happens on your phone

Video is exactly the case where uploading is worst. Files are large, they are frequently personal, and a converter with a server has to move every byte of your footage to a machine you do not control, keep it there while it works, and be trusted to delete it afterwards.

Convexy has no server. The export runs on your device's own video hardware, which is why it works in Airplane Mode, needs no account, and does not care how big the clip is.

How to do it

  1. Bring the MOV into Convexy

    Tap Browse files to pick it from Files, choose it from Photos, or share it straight into Convexy from any app.

  2. Choose MP4

    Convexy offers only what the file can actually become — MP4, M4V, animated GIF, extracted audio, or a still frame.

  3. Pick codec and quality

    Choose H.264 for maximum compatibility. Choose Original quality to preserve resolution, or a lower preset to shrink the file.

  4. Check the audio toggle

    Include audio is on by default. Turn it off only if you genuinely want a silent clip.

  5. Convert, then save or share

    The export runs on your device's video hardware. Save the MP4 to Files or Photos, or share it directly.

Common questions

Is MOV to MP4 lossless?

Not in Convexy. It re-encodes the video through Apple's export pipeline rather than remuxing the existing stream untouched, so it is a new lossy generation. In exchange you get real control over resolution and codec. Choose "Original" quality to stay as close to the source as possible. For ordinary purposes — sharing, uploading, editing — a single careful re-encode is not something you will see.

Can I just rename the .mov file to .mp4?

Sometimes it works, and it is a bad habit. The containers are closely related, so some players will cope — but many will not, and if the video inside is HEVC you have solved nothing, because the recipient's real problem is usually the codec, not the extension. A proper conversion with H.264 selected is the fix that actually holds.

Why won't my iPhone video play on Windows?

Almost always because it is HEVC (H.265), not because it is a MOV. Convert it to MP4 with the codec set to H.264 and it will play essentially everywhere. If you want to stop the problem at source, set Camera to "Most Compatible" in iOS Settings and the phone will record H.264 from the start.

Will the MP4 be smaller than the MOV?

It depends entirely on what you choose, not on the container. Re-encoding a HEVC MOV to H.264 at the same resolution will typically make it bigger, because H.264 is less efficient. Downscaling to 720p or 1080p will make it much smaller. The container itself changes almost nothing about size.

Does converting video upload it anywhere?

No. Convexy has no backend. The conversion runs on your iPhone or iPad using its own video hardware, works with the network off, and never sends a byte of your footage anywhere — which matters more for video than for almost anything else.