Video Format Converter
Convert a video to WebM, MP4, MKV, MOV, AVI, OGV, MPEG, FLV, 3GP, WMV, TS or M4V. Choose the output format and the tool picks the right codecs — copying the streams instantly when the new format can hold them, and re-encoding with full control over quality, bitrate, resolution and audio when it cannot.
Also: MKV to MP4 converter · AVI to MP4 converter · MOV to MP4 converter · WebM to MP4 converter · FLV to MP4 converter · TS to MP4 converter · WMV to MP4 converter · MPEG to MP4 converter · 3GP to MP4 converter · M4V to MP4 converter · MOD to MP4 converter · VOB to MP4 converter · MTS to MP4 converter · OGV to MP4 converter · RM/RMVB to MP4 converter · MXF to MP4 converter · MP4 compressor · Video to MP3 extractor · MP4 to GIF converter
Click to choose a video, or drag and drop
Choose a video in any common format. Stays on your device, nothing is uploaded.
Your video is converted entirely in your browser and is never uploaded. The converter engine (ffmpeg, ~32 MB) is downloaded once and cached by your browser.
Frequently asked questions
How do I convert MP4 to WebM?
Choose your MP4, leave the output format on WebM, and click Convert video. WebM here uses VP8 video with Opus audio, which plays in all modern browsers. VP8 files are somewhat larger than MP4 at the same quality, so use the Small file preset if size matters. For a long video, use Start and End to convert just a part.
Which format should I choose?
MP4 plays everywhere and is the safe default. WebM is best for websites and chat apps that support it. MKV holds almost anything and is ideal for keeping every audio track and subtitle. MOV and M4V suit Apple devices and editors. AVI, MPEG, WMV, FLV and 3GP are for old players, phones and software that need them.
When is the video copied instead of re-encoded?
When the new format can hold the video and audio exactly as they are, for example H.264 and AAC going from MP4 to MKV or MOV, or VP9 and Opus from MP4 to WebM. The tool detects this and copies the streams, which finishes in seconds with no quality loss. Otherwise it re-encodes, and the note under Output format tells you which streams are converted.
Why do some formats limit my choices?
Each format can only hold certain codecs: WebM takes VP8 (or an existing VP9/AV1 video, copied) with Opus or Vorbis audio, OGV takes Theora and Vorbis, WMV takes WMV2 and WMA, and so on. The video and audio codec menus show only what the chosen format supports, and the tool warns if a combination will not work.
Can I convert to H.265 or AV1?
No. The in-browser engine cannot encode H.265, VP9 or AV1. It can copy an existing stream of those types into a compatible container, and it offers H.264, VP8 and several older codecs for new encodes. For other needs, see the MP4 compressor, the MP4 to GIF converter and the video to MP3 extractor.
Is my video uploaded anywhere?
No. The conversion runs entirely in your browser using ffmpeg compiled to WebAssembly. Your video never leaves your device. Only the converter engine itself (about 32 MB) is downloaded, once, and cached by your browser.
What do CRF and bitrate mean?
CRF (constant quality) lets the encoder spend as many bits as each scene needs: lower numbers mean better quality and bigger files, around 18 looks near-lossless, 23 is the default and 28 is noticeably smaller. A target bitrate instead aims for a fixed number of kilobits per second, which gives a predictable file size but variable quality.
Why is re-encoding slow, and is there a size limit?
Re-encoding runs on a single CPU thread inside the browser (H.264 only), so it is usually near real-time speed or slower for HD. The finished MP4 also has to fit in browser memory, which in practice limits output to roughly 1 to 2 GB. For a long movie, use Fast remux, trim it, or copy the generated command and run it with ffmpeg on your own computer.