Useful bitrate choices
Choose 128 kbps for spoken audio, 192 kbps for a balanced default, or 320 kbps when minimizing another lossy step matters.
MP4 to MP3 Converter
Convert MP4 video to MP3 locally in your browser with 128, 192, or 320 kbps quality and optional trimming. No upload, account, or watermark.
Local conversion workspace
Convert video to audio
Your video stays on this device. Processing starts only after you click Convert.
0 bytes uploaded
0 bytes uploadedMulti-thread mode is used only when this browser supports SharedArrayBuffer and cross-origin isolation.
MP4 to MP3
A practical MP3 workflow
Turn the audio inside an MP4 into a file that plays almost everywhere.
Trim before encoding
Set a start and end point so you only encode and download the part you need.
Local processing
The MP4 is decoded and the MP3 is encoded in a browser worker without uploading the file.
Workflow
How to convert MP4 to MP3
Use the final source file and make the output choice explicit.
Select the MP4
Choose one MP4 up to 300 MB and wait for the browser to read its duration.
Set MP3 quality
Keep 192 kbps for a reliable default or move down for speech and up for music.
Convert and check
Download the result, play it, and keep the source MP4 until the audio is verified.
Privacy boundary
The MP4 stays on your device
ffmpeg.wasm performs the conversion inside this browser tab.
- No media upload is required
- Cancel terminates the worker
- Finished tasks release the temporary file system
FAQ
MP4 to MP3 questions
Answers about quality, codecs, speed, and local processing.
MP3 is lossy, so it introduces another encoding stage. A higher bitrate reduces added loss but cannot improve the source.
128 kbps is usually enough for speech; 192 kbps is a safer default when the file includes music or effects.
320 kbps MP3 still uses lossy compression. It discards less than lower MP3 bitrates but is not equivalent to WAV or stream copy.
Yes. Some screen captures, animations, and exported clips contain only a video stream.
The browser must decode and re-encode audio using WebAssembly, which is slower than native desktop FFmpeg.
No. The file is processed in the browser worker and is not sent to our conversion server.