Convert a Video to MP4
Drop a MOV, MKV, AVI, WMV, WebM or 3GP video: it's converted to MP4 (H.264 + AAC), which plays on almost every device. The conversion runs in your browser, with no upload.
- MOV, MKV, AVI, WebM…
- Lossless when possible
- Time remaining shown
- 100% private
100% private — Everything is processed directly in your browser: your files, voice, and image are never sent to Chatzam's servers.
How to convert a video to MP4?
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Import the video
Drag the file into the box or select it: iPhone MOV, MKV, AVI, WMV, FLV, WebM, 3GP…
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Follow the conversion
If the video is already in H.264 and AAC, only its container changes, almost instantly. Otherwise, it's re-encoded, with a progress bar and the time remaining.
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Download the MP4
Get your MP4 file, ready to play on a phone, a computer or a TV, or to be shared.
An MP4 that plays everywhere, no software needed
All common formats
MOV (iPhone), MKV, AVI, WMV, FLV, WebM, 3GP: old and recent videos alike are supported.
Lossless when possible
A video already encoded in H.264 and AAC is simply placed in an MP4 container: no quality loss, and it's nearly instant.
High-quality re-encoding
Other videos are re-encoded to H.264 with AAC audio, the most compatible combination, while keeping good image quality.
Nothing is uploaded
The FFmpeg engine runs in your browser (about 30 MB, downloaded once): your video never leaves your device.
Why convert a video to MP4?
MP4 with H.264 video and AAC audio is the most universal video format: it plays on iPhone and Android, on Windows and macOS, in every browser and on most TVs, and it's accepted by messaging apps and social networks. Other formats often cause trouble: an MKV or AVI won't open on a phone, a WMV won't play on a Mac without extra software, a WebM is rejected by some websites, and an iPhone MOV video sometimes shows up with no picture on a PC. Converting to MP4 fixes these compatibility issues without installing a player or any software.
iPhone MOV to MP4: container and codec
A file extension (.mov, .mkv, .mp4) refers to a container, a kind of envelope; inside, the video and audio are compressed with codecs. If your video already contains H.264 video and AAC audio, like many MOV and MKV files, the tool moves it as is into an MP4 container: no quality loss, and it's very fast, even for a long video. Since iOS 11, the iPhone records in HEVC (H.265) by default, with the “High Efficiency” setting: these videos have to be re-encoded to H.264, which takes longer but makes them play everywhere. For future videos, the “Most Compatible” option, in Settings > Camera > Formats, records directly in H.264.
Large files: what you need to know
The conversion uses your device's processing power, not a server's. The first time, the FFmpeg engine (about 30 MB) is downloaded, and then it doesn't need to be loaded again. A simple container change is very fast; re-encoding takes longer depending on the length and resolution of the video: a few minutes of 4K footage take some patience, especially on a phone. Files of several GB can be very slow, or even impossible to process on a small device: use a computer if you can, and keep the tab open during the conversion. To make the MP4 smaller afterwards, use “Compress Video”; to keep only a clip, “Cut / Trim Video”; to extract just the audio, “Convert MP4 to MP3”.
Frequently Asked Questions
How do I convert a MOV video to MP4?
Drop the MOV file on this page: it's converted to MP4 in your browser, then you download it. If it's already in H.264, the conversion is nearly instant and lossless.
Does converting to MP4 reduce quality?
Not if the video is already in H.264 and AAC: only its container changes. Otherwise, it's re-encoded aiming for good quality, and the difference is usually hard to see.
Why won't my iPhone video play on Windows?
It's probably in HEVC (H.265), the iPhone's “High Efficiency” format, which Windows can't always play without an extra extension. Once converted to H.264 MP4, it plays everywhere.
How long does the conversion take?
A few seconds if the video is already in H.264 and AAC. Otherwise, it depends on the video's length and resolution and on your device's power; the progress bar shows the time remaining.
Is my video uploaded to a server?
No. The conversion happens in your browser thanks to FFmpeg: the video never leaves your device. It's free, with no sign-up.