How long does the conversion take?

That depends entirely on the content and size of your file. If the video inside is already H.264, only the container changes, the data is copied across and the job usually finishes very quickly. But if there is a codec such as ProRes in there, the picture has to be re-encoded, and on long, high-resolution files that can run for minutes. Upload and download times are added on top according to your internet speed, so be patient with large files.

My audio disappeared after converting, what should I do?

This usually happens because the original MOV contains an audio codec that MP4 cannot carry directly; uncompressed PCM audio is common in recordings. The fix is to convert by encoding the audio track to AAC, which is what a normal conversion flow already does. If your file has more than one audio track, some tools take only the first one and the track you wanted can be dropped. In that case it helps to check which track sits in which position in the source file.

The video came out rotated 90 degrees, why?

Videos shot vertically on a phone are actually recorded horizontally, and a rotation metadata flag meaning 'display this turned by so many degrees' is written into the container. Some players and some conversion flows ignore that flag, and the picture ends up sideways. Using a conversion that preserves the rotation information, or applies the rotation permanently to the picture, resolves it. Checking the result on a desktop player rather than on your phone also lets you see the real situation.

My file is very large, should I shrink it before uploading?

Usually there is no need, because the conversion itself can already drop the size considerably. A MOV containing ProRes in particular becomes a far smaller file once it turns into H.264 MP4. But if your upload speed is very low, or the file is a recording several hours long, splitting the video or lowering the resolution first may be more practical. Avoid compressing twice in a row, because every re-encode takes a little more quality away.

Converting a MOV File to MP4: A Step-by-Step Guide

Before you start: which kind of file do you have?

Moving from MOV to MP4 looks like a single uniform operation from the outside, but there are really two entirely different scenarios, and knowing which one you are in determines both how long the job takes and how good the result is.

MOV is a container, meaning a box that can hold picture compressed with different codecs inside it. iPhone, iPad, GoPro and most screen recording software write H.264 or H.265 into the MOV box. Professional cameras and editing programs, on the other hand, frequently use ProRes.

This distinction matters for one reason: the MP4 container can carry H.264 and H.265, but it cannot carry ProRes. So in the first group the job is only "changing the box"; in the second the picture has to be compressed from scratch.

The easiest way to work out which group your file belongs to is to look at where it came from. Did it come off a phone? Almost certainly H.264 or H.265. Did it come from a cinema camera or a Final Cut Pro export? Probably ProRes, and the file size gives it away — hundreds of megabytes per minute is ProRes's signature.

Step-by-step conversion

1. Upload the file

Open our MOV to MP4 converter and drag and drop your file in. On large files the upload stage itself takes time; do not close the browser tab while it runs.

2. Wait for the tool to read the file

In this short stage the video and audio codecs inside are detected. The outcome of that detection determines whether the job will be a remux or a re-encode.

3. Start the job and wait

Set your expectations correctly here: a container swap finishes quickly, a re-encode takes a long time. For a ten-minute 4K recording the job may run for minutes, and that is normal. Even if progress looks like it has stalled, wait a few more minutes — encoding does not always advance at an even pace.

4. Download the result

When the file is ready, download it and do not delete the original straight away. Keep the source file to hand until you have verified the conversion.

Always check after downloading

It is not enough for a conversion to look "successful". Verify these four things quickly:

Is the duration the same? The new file's duration should match the original. If it is shorter, the job may have been cut off part way.
Is there audio, and is it in sync? Open a point in the middle and at the end, not just the start of the video. Sync drift usually shows up later on rather than at the beginning.
Is the orientation right? Especially with videos shot vertically on a phone, check whether the picture has ended up sideways.
Is the picture quality acceptable? If a re-encode was done, look for degradation in detailed scenes (crowds, foliage, water).

Do the checking on a computer if possible, not on a phone screen. A small screen hides plenty of quality problems.

Common problems and their fixes

The file will not upload or the job will not start. This is usually to do with the file size limit. With very long recordings, splitting the video into parts first is a practical solution. Your connection's upload speed is also decisive here — your upload speed can be low even when your download speed is high.

The output file is much bigger than I expected. If the source file already contained H.264 and a remux was performed, the size stays almost the same — that is not a fault, it is the natural result of a lossless operation. If you want to reduce the size you need a separate compression step, and that step comes with a quality cost.

The output file is much smaller than I expected and the quality looks poor. This is the case where a barely compressed source such as ProRes has been encoded to H.264. The large drop in size is an expected outcome. But if there is visible degradation in the picture, it is worth trying to re-encode the source at a higher bitrate.

Audio and picture have drifted apart. This is a typical problem with screen recordings captured at a variable frame rate. With files like these, a process that converts to a constant frame rate gives a more reliable result.

The file will not open in a player. Rarely, a conversion can finish incompletely. If the file size is suspiciously small, run the job again.

How long does it take? Setting the right expectation

There is no single answer to this question, and the reason is that what determines the time is not the file size but the type of work being done.

In a container swap the work the computer does amounts to copying data; the picture is never decoded. That is why even a file of several gigabytes can be processed surprisingly quickly — the limiting factor is usually the speed of the disk and the connection.

In a re-encode, each frame is decoded one by one and compressed again from scratch. What matters here is resolution, duration and the complexity of the scenes. Sections with movement and detail process noticeably more slowly than static shots, which is why the progress bar moves irregularly. That is not a fault, it is the natural rhythm of encoding.

To that you have to add transfer time. On large files the upload can take even longer than the processing itself on most home connections — because upload speed is usually markedly below download speed.

The matter of renaming the extension by hand

There is a suggestion you often come across online: renaming the file from video.mov to video.mp4. Because MOV and MP4 are related formats this sometimes works and the file opens.

Even so, it is not a reliable method. Changing the extension does not touch the structure inside the file; some header fields within the container may not fully conform to the MP4 standard, and the file can be rejected by some players, and particularly by the validation checks of platforms you upload to. With a MOV containing ProRes this method solves nothing at all, because the problem is not in the extension but in the codec.

In conclusion

Moving from MOV to MP4 is often a more harmless operation than you think. If the file in your hands came off a phone, it will most likely be converted with no quality loss, with only the container changed. If it came from a professional source, a re-encode will be needed and some quality loss will be unavoidable — going in knowing that is the best way to avoid disappointment later.

Whatever the case, pick up one habit: after converting, actually open the file and check its duration, its audio and its orientation. That thirty-second check is far cheaper than the trouble of noticing a problem only after you have uploaded the wrong file somewhere.