Convert Video to MP4
Change a video's container without changing the video. Where the codec inside already fits the target, the streams are copied across untouched — identical quality, finished in seconds. Where it does not, the tool says so before it starts instead of after you have waited. Nothing is uploaded.
A container is not a codec
MP4, MOV, MKV and WebM are containers — wrappers that hold streams and describe how they line up in time. The video itself is a codec: H.264, H.265, VP9, AV1. Converting between containers usually means moving the same streams into a different wrapper, which is a copy, not a conversion.
That is why "convert MOV to MP4" and "convert WebM to MP4" are completely different jobs even though they read the same. A MOV from a phone already holds H.264, which an MP4 carries natively — nothing to do but rewrite the wrapper. A WebM holds VP9, which an MP4 cannot carry in any way other software will open, so every frame has to be decoded and re-encoded.
Server-side converters mostly re-encode regardless, because it is simpler and they are charging for the machine time anyway. Here the difference is yours to keep: a copy costs nothing and loses nothing.
What each target copies
| Target | Copied without re-encoding | Otherwise re-encoded to |
|---|---|---|
| MP4 | H.264, H.265 | H.264 |
| WebM | VP9, AV1, VP8 | VP9 |
| MKV | H.264, H.265, VP9, AV1, VP8, ProRes | H.264 |
| MOV | H.264, H.265, ProRes | H.264 |
MKV copies the widest range, which is why it is the fastest target and the right answer when you control what plays the file. MP4 is the most compatible and the most selective — it is the only row where a codec the container technically accepts still gets re-encoded, because a legal file nothing can open is not a useful result.
Start from your format
Frequently asked questions
Why is this so much faster than other converters?
Because most conversions do not need to convert anything. A video file is a container holding separate streams, and if the codec inside is one the target container can carry, the packets are copied across untouched — no decoding, no re-encoding, no quality loss. That takes about as long as reading the file. Only when the codec genuinely does not fit does anything get re-encoded.
Will the quality change?
Not on the copy path — the output is bit-for-bit the same video stream, so the picture is identical to the source. On the re-encode path you lose one generation, the same as any other converter. The tool tells you which one it is doing before you start, so it is never a surprise afterwards.
Is my video uploaded?
No. The file is read and rewritten by your own browser. Nothing is sent to a server, there is no queue, and there is no size allowance to run out of.
Why does converting to MP4 sometimes re-encode?
Because MP4 accepting a codec and a player being able to open the result are different questions. An MP4 will technically hold VP9, and the file it produces plays in Chrome and almost nowhere else — not QuickTime, not Premiere, not a TV. Handing you that would mean a file with the right extension and the wrong contents, so those cases re-encode to H.264 instead.
Which format should I pick if I just want it to work?
MP4 for phones, editors, social platforms and anything you are sending to someone else. MKV if you want the conversion to be instant and you control what plays it — Matroska accepts nearly any codec, so it almost never has to re-encode. WebM only for the web.
Why is AVI slower than everything else?
AVI, WMV and FLV are older containers the fast reader cannot open, so those files need a fuller converter downloaded first — about 30 MB, once. It also holds the whole file in memory rather than streaming it, so files over roughly 200.0 MB may not finish. Every other format on this page avoids that entirely.
What happens to extra audio tracks and subtitles?
The primary video and audio streams are carried over; additional tracks are not. That matters most for MKV rips with several languages, which is exactly the case where an MP4 could not represent them anyway.
Is there a file size limit?
Up to 2 GB on the fast path, because the file is streamed rather than held whole in memory. The fallback engine used for AVI and WMV is the exception — see above.