MOV to MP4
How to convert MOV to MP4 without losing quality
Whether a MOV to MP4 conversion costs you quality depends on the codec inside the file, not on the two extensions. Here is how to check what you have, what the browser converter does with it, and how to avoid the problem on your next recording.
A MOV converts to MP4 with no quality loss when it holds H.264 video and AAC audio: the streams are copied into an MP4 container and nothing is re-encoded. A HEVC clip, the default on iPhones that support it, has to be re-encoded to H.264 to play everywhere, and that step costs a little quality.
What is the difference between MOV and MP4?
MOV is the QuickTime container, made by Apple. MP4 (MPEG-4 Part 14, ISO/IEC 14496-14) was built on top of the QuickTime file format, so the two are close relatives and often carry the same video and audio. A container is only the box. The picture quality is set by the codec that compressed the video, and changing the box does not touch the picture inside.
When is the conversion lossless?
It depends on the codecs inside the MOV. This is how the in-browser MOV to MP4 converter handles each case:
| Inside the MOV | What the converter does | Quality afterwards | Time |
|---|---|---|---|
| H.264 video + AAC audio | Copies both streams into an MP4 | Identical to the original | A second or two |
| H.264 video + other audio | Copies the video, encodes the audio to AAC | Video identical, audio re-encoded | Seconds |
| HEVC (H.265) video | Re-encodes the video to H.264 | A small loss | As long as the encode takes |
How can I tell which codec my MOV uses?
- On a Mac: select the file in Finder, press Cmd+I and open More Info. The Codecs line names the video and audio formats.
- On an iPhone: Settings, Camera, Formats. High Efficiency records HEVC, Most Compatible records H.264.
- No tool at hand: run the conversion. A copy finishes almost at once, while a long progress bar means the video is being re-encoded.
How do I convert a MOV to MP4 in the browser?
- Open the MOV to MP4 page and drop the clip on the box, or pick it from your disk. One file at a time, up to 1 GB.
- Press Convert to MP4 and wait for the bar to finish.
- Download the result. It keeps the original name with an .mp4 extension, and the MOV stays untouched on your disk.
The work happens in your browser tab, so the clip is not uploaded. It relies on the browser's WebCodecs support: recent Chrome and Edge, Firefox 130 or later, or Safari 16.4 or later.
What does not come along?
- Only the main video track and the main audio track are converted. A second audio track, subtitles or a timecode track stay behind.
- A HEVC re-encode is lossy. At the same resolution the difference is hard to see on video, but it is not a bit-for-bit copy. If you need the exact original, keep the MOV.
- The converter does not make files smaller. A copy comes out at about the size of the source. For a smaller file, use the video compressor as a separate step.
Can I avoid converting at all?
Yes. On an iPhone, Settings, Camera, Formats, Most Compatible makes new videos H.264, so a later conversion is a plain copy. The price is storage: Apple says HEVC gives the same visual quality as H.264 in less space, so Most Compatible files are larger. Apple documents the setting at support.apple.com/en-us/116944.
Questions
Does converting MOV to MP4 reduce quality?
Not when the MOV holds H.264 video, because the stream is copied unchanged. A HEVC video has to be re-encoded to H.264, which loses a little. Check the codec first: if it says HEVC, expect a small, hard-to-see loss.
Why does my iPhone video not play on Windows or Android?
Usually the codec is the cause, not the .mov extension. Recent iPhones record HEVC, and a player without a HEVC decoder may show a black picture or play only the sound. Converting to H.264 in an MP4 plays almost everywhere.
Can I just rename a .mov file to .mp4?
Renaming changes the label, not the file. It may play in a player that reads the contents instead of the extension, but the file is still a QuickTime MOV, and a HEVC video inside is still HEVC. A real conversion rewrites the container.
Is the video uploaded when I convert it?
No. The file is read, converted and saved inside your browser tab, and nothing is sent to a server.
How big a MOV can I convert?
Up to 1 GB per file, one file at a time. The whole file is processed in your browser's memory, so a very large clip may need a desktop browser rather than a phone.