About this mp4 to mp3 converter
Turn a recorded lecture, podcast video, voice note or music performance into an MP3 you can play anywhere. The conversion uses ffmpeg with the LAME MP3 encoder inside your browser, so private recordings never leave your device.
How to use the MP4 to MP3 Converter
- Drop a video file (MP4, MOV, WebM, MKV and more).
- Choose a bitrate: 192 kbps suits most music, 128 kbps or Mono is plenty for speech.
- Optionally enter a start and end time to keep only part of the audio.
- Press Convert to MP3, listen to the preview and download.
Features
- High-quality LAME MP3 encoding from 128 to 320 kbps.
- Optional trimming and mono output for smaller files.
- Works with iPhone MOV and screen recordings.
- Built-in audio preview before you download.
Frequently asked questions
What bitrate should I choose?
192 kbps is near-transparent for most listeners. Use 320 kbps for music you care about, and 128 kbps or Mono for lectures and podcasts.
Will 320 kbps improve a low-quality source?
No. MP3 can’t add detail that isn’t in the original audio. If the video has 128 kbps AAC audio, a higher bitrate only makes the file larger.
Can I convert a YouTube video to MP3?
ToolBox doesn’t download from YouTube. You can convert videos stored on your own device that you have the rights to use.
Why did conversion fail?
The video may have no audio track, or the file may be damaged. Try playing it first; if it plays with sound, try again in Chrome or Edge.
Is my file uploaded?
No. Everything happens locally with WebAssembly; only the ffmpeg engine itself is downloaded from a CDN.