Video to MP3
Extract the sound of an MP4, MOV, WebM or MKV video as an MP3 file in your browser. Choose the bitrate, keep only a part, nothing is uploaded.
Times as seconds (75.5) or minutes:seconds (1:15.5). Keep the whole length to extract all the audio.
Your browser's own decoder handles most MP4 and WebM files instantly. Other formats, and videos longer than 10 minutes, use FFmpeg compiled to WebAssembly: the first time, about 30 MB are downloaded, then kept in your browser's cache. A browser is slower than desktop software on very large files.
How to extract the audio from a video
- Drop a video on the box above, or click it to choose a file (up to 500 MB).
- The video appears with a position slider. To keep only part of the sound, play or scrub to the right moment and press Set start here, then Set end here. You can also type the times, as seconds (
75.5) or minutes:seconds (1:15.5). Leave the whole length selected to extract everything. - Press Play selection to check the part you chose.
- Pick the MP3 bitrate and the Channels: Same as the video, or Mono (half the size for speech).
- Press Extract MP3. A progress bar appears with a Cancel button. When it is done, listen to the result in the player and download it.
The line next to the button shows the length of the MP3 and its approximate size before you start.
How it works
A video file is a container holding separate streams: usually one video track and one audio track, often in AAC (MP4, MOV) or Opus/Vorbis (WebM, MKV). This tool reads the audio track and re-encodes it as MP3 with the LAME encoder, the reference MP3 encoder.
There are two ways it can do this, both entirely on your device:
- Fast path. For most MP4 and WebM files up to 10 minutes long, your browser’s own decoder (the Web Audio API) turns the sound into raw samples, which are then encoded to MP3. This is almost instant and needs no extra download.
- FFmpeg. For formats your browser can’t decode (AVI, WMV, many MKV files, some MOV files), for longer videos, or when the fast path fails, the tool uses FFmpeg compiled to WebAssembly. The first time, about 30 MB are downloaded and then kept in your browser’s cache. FFmpeg reads the file in slices, so even large videos don’t have to fit in memory at once.
Your file never leaves your computer: there is no upload and no server-side processing.
Choosing the bitrate
The MP3 bitrate is a constant bitrate (CBR), so the size is easy to predict: size in bytes ≈ bitrate × duration ÷ 8. One minute at 192 kbps is about 1.4 MB.
| Bitrate | Good for | Size per minute |
|---|---|---|
| 96 kbps | Speech, lectures, podcasts (use mono) | ~0.7 MB |
| 128 kbps | Speech in stereo, casual listening | ~0.9 MB |
| 192 kbps | Music: a good default | ~1.4 MB |
| 256–320 kbps | Music you want to keep at the best MP3 quality | 1.9–2.3 MB |
Re-encoding can’t add quality that isn’t there: if the video’s soundtrack is AAC at 128 kbps, choosing 320 kbps only makes a bigger file. For a voice recording, Mono (half the size for speech) loses nothing audible.
Limits
- Up to 500 MB per video. A browser is slower than desktop software on very large files, and the FFmpeg route uses more memory; for multi-gigabyte recordings, desktop tools such as FFmpeg or VLC are better suited.
- If a video has several audio tracks (languages, commentary), the first one is extracted.
- A video without sound gives the message “This video has no sound track.”
- Protected (DRM) videos from streaming services can’t be read.
Frequently asked questions
Is my video uploaded anywhere?
No. The file is read by your browser and processed on your device. You can even disconnect from the internet once the page (and, if needed, the conversion engine) has loaded.
Why does it download 30 MB the first time?
That is FFmpeg, the conversion engine, compiled to WebAssembly. It is only needed for formats your browser can’t decode itself or for long videos. Your browser keeps it in its cache, so the next conversions start right away.
Can I extract only a part of the soundtrack?
Yes. Set a start and an end with Set start here and Set end here, or type the times, then press Extract MP3. Only that part is encoded, which is also faster.
Which bitrate should I choose?
192 kbps is a good default for music and 96 or 128 kbps in mono is plenty for speech. A bitrate higher than the source’s audio doesn’t improve quality, it only makes the file bigger.
Why is it slow on a long video?
When the browser can’t decode the file itself, FFmpeg runs in WebAssembly on a single processor core, which is slower than a native program. Extracting audio is still much quicker than converting the video itself, because the picture is skipped entirely.
Can I convert to another format than MP3?
This tool always produces MP3, the format that plays everywhere. For WAV, OGG, M4A or FLAC, drop the video on the audio converter instead: it can extract the sound from a video too.
Related tools
- Audio Converter Convert audio files to MP3, WAV, OGG, M4A or FLAC in your browser, or extract the sound of a video. Batch conversion, no upload, no sign-up.
- Video Trimmer Trim an MP4, MOV, WebM or MKV video in your browser. Pick the start and end on a preview, cut fast without re-encoding or frame-exact. No upload.
- Audio Cutter Cut and trim MP3, WAV, M4A, OGG or FLAC files in your browser. Select on the waveform, add fades and export to MP3 or WAV. No upload.
- Video Compressor Compress a video in your browser to share it by email or chat. Choose a quality or a target size in MB, lower the resolution, no upload.