Free · no signup · never uploaded
MP4 to MP3 Converter
Extract the audio track from an MP4 video as a 192 kbps MP3 — right in your browser, no upload, no watermark.
Short answer
To convert MP4 to MP3, drop your video below and download the extracted MP3 audio. It runs entirely in your browser with ffmpeg — your video is never uploaded, so it’s private and works offline after the first load. The audio is saved at 192 kbps.
Why extract MP3 audio from an MP4?
Pulling the audio out of a video lets you keep a lecture, podcast, interview, or song without the picture — playable on any music app and a fraction of the size. An MP3 holds just the sound, so a large MP4 becomes a small, universally-playable audio file.
Is the audio quality good?
The MP3 is encoded at 192 kbps — a high-quality setting that’s transparent for speech and very good for music while keeping files small. MP3 is lossy, so it can’t add back detail the MP4’s audio didn’t already contain, but at 192 kbps the difference is inaudible to most listeners.
MP3 bitrate, size and quality
| Bitrate | Per minute | Per hour | Best for |
|---|---|---|---|
| 128 kbps | 1.0 MB | 58 MB | Speech, podcasts, voice notes |
| 192 kbps | 1.4 MB | 86 MB | Music — transparent to most listeners — used by these tools |
| 256 kbps | 1.9 MB | 115 MB | Music on good headphones |
| 320 kbps | 2.4 MB | 144 MB | The maximum MP3 allows |
MP3 file size is almost purely bitrate × duration, so you can predict it exactly: a three-minute song at 192 kbps is about 4.3 MB regardless of what the original was. Above roughly 192 kbps most listeners cannot pick MP3 from the original in a blind test.
How we calculate this
Conversion happens locally in your browser with ffmpeg — here is exactly how:
- Load the engine. ffmpeg compiled to WebAssembly loads once in your browser from this site (self-hosted, not a third party) — your file is never uploaded.
- Decode. ffmpeg reads the MP4 video and decodes its audio (any video stream is dropped with -vn).
- Encode to MP3. the audio is re-encoded to MP3 at 192 kbps constant bitrate and handed back as a download.
Assumptions
- Everything runs client-side; speed depends on your device and the clip length.
- MP3 is lossy at 192 kbps and cannot exceed the quality of the source audio.
- Very large or long files are limited by your browser's available memory.
Last reviewed: July 19, 2026
Frequently asked questions
How do I convert an MP4 to MP3?+
Drop your MP4 in above and download the MP3 the tool extracts. The whole conversion runs in your browser with ffmpeg, so your video is never uploaded. The first conversion loads the converter (about 31 MB) once; after that it's instant.
Are my videos uploaded to a server?+
No. Everything runs 100% in your browser using ffmpeg compiled to WebAssembly, so your MP4 never leaves your device. Nothing is stored or sent anywhere — it's private, and works offline once the converter has loaded.
What quality is the MP3?+
The audio is encoded at 192 kbps constant bitrate, a high-quality setting that sounds great for both speech and music while keeping the file small.
Why is the first conversion slower?+
The first time, your browser downloads the ffmpeg engine (about 31 MB) and starts it up. That happens once — subsequent conversions reuse the loaded engine and are much faster.
Is there a file-size limit?+
There's no fixed limit, but because the conversion runs in your browser's memory, very large or long videos can be limited by your device's available RAM.
Does it keep the whole audio track?+
Yes. The full-length audio is extracted from start to finish — only the video picture is dropped. The result is the complete soundtrack as an MP3.
Related tools
- MOV to MP3 — extract audio from an iPhone .mov video.
- WAV to MP3 — shrink a WAV recording into an MP3.
Audio is extracted entirely in your browser with ffmpeg and never uploaded. MP3 is encoded at 192 kbps.