mp4 to mp3 converter online free

To be upfront about what this tool does and does not do: it converts a video file you upload from your own device into an MP3. It is not a YouTube-to-MP3 downloader and does not accept a video URL — you need the MP4 file itself already saved locally before you can convert it. If your goal is downloading audio from an online video platform, that is a different kind of tool and usually runs into each platform's own terms of service; this one stays strictly local, working only on a file you already have.

The audio is encoded with LAME at VBR quality level 2, which produces a variable bitrate MP3 that typically lands around 190kbps — close to transparent for most listeners and noticeably better than the flat 128kbps many free converters default to. There is no manual quality slider for this specific conversion, since the fixed VBR-2 setting already gives a strong quality-to-size balance without needing to be tuned per file.

Conversion strips the video stream entirely and keeps only the audio track, so a two-minute 1080p video and a two-minute audio-only recording of the same length will produce a similarly sized MP3, regardless of how large the original video file was. This makes MP4-to-MP3 conversion a genuinely effective way to shrink a large video down to something easy to store or share when you only need the sound.

Everything happens locally in your browser using FFmpeg compiled to WebAssembly. The uploaded video is never sent to a server, which matters if the source video contains anything private — a recorded meeting, a personal video, a voice memo captured as a video file — since the audio extraction never leaves your device.