Video Converter: MOV, MKV, WebM to MP4
Switch MOV, MKV, WebM or TS videos to MP4 (or WebM/MOV) in your browser, with no upload and often no re-encoding.
or drop it here
Accepts: MP4, MOV, WebM, MKV, TS
Converted on this device. Your files are never uploaded.
A container is the box; the codec is what's inside
MP4, MOV, MKV and WebM are containers: they hold a video stream, audio streams and timing information. The codec (H.264, HEVC, VP9, AV1, AAC, Opus and so on) is how each stream is compressed.
The MP4 format is derived from Apple's QuickTime (MOV) format, which is why the two often carry the same H.264 or HEVC video and AAC audio.
If the codecs fit, it's a copy, not a conversion
When the new container allows the existing codecs, the streams are copied as they are. That is near-instant and the picture is unchanged; many iPhone MOV files become MP4 this way.
When they don't fit, the streams are re-encoded. Choosing MP4 or MOV turns VP9 or AV1 video into H.264 (or HEVC if H.264 isn't available) and Opus or Vorbis audio into AAC, so the file plays on iPhone, Mac and in editing apps. WebM only allows VP8, VP9 or AV1 video with Vorbis or Opus audio, so an H.264 MP4 has to be re-encoded to become WebM.
What your device can decode matters
Re-encoding uses the browser's WebCodecs, which can use the device's hardware. HEVC (H.265) decoding depends on the device's hardware and operating system, so an iPhone HEVC video may convert on one computer and not on another.
Long, high-resolution videos need a lot of memory, and phones can fail where a computer succeeds.
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Questions
Why is MP4 the default?
MP4 with H.264 video and AAC audio is accepted by almost every phone, TV, editing app and website, so it's the safest target.
Will MOV to MP4 lower the quality?
Not when the streams can be copied, which is the usual case for iPhone videos. If re-encoding is needed, there is some loss, as with any lossy encode.
Will the file get smaller?
A stream copy keeps the size about the same. To shrink a video, use Compress video.
Why did my WebM to MP4 conversion take longer?
WebM files usually hold VP9 or AV1 video and Opus audio, so for MP4 they're re-encoded to H.264 and AAC, which takes time. Files that already hold H.264 or HEVC with AAC are copied almost instantly. If your browser can't create H.264 or HEVC video, the page tells you.
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