Convert MP4 to MP3
The audio, without the video — extracted on your own device in one pass, ready for your phone, car, or podcast app.
Drop your video or audio here
or
MP4, MOV, WebM, MKV, AVI, MP3, WAV and more — any size, no upload
🔒 Files never leave your device — everything runs in your browser.
MP4 to MP3 is the internet's most-wanted conversion for a simple reason: so much audio worth keeping arrives wrapped in video — recorded lectures, concert clips, interviews, meditation sessions, podcast episodes published only as video. An MP3 plays on literally everything, takes a tenth of the space, and lives happily in your music app.
ConvertUno pulls the audio track straight from your MP4 without the file ever leaving your device — which also makes it dramatically faster than upload-based converters for big videos. If the MP4's audio is already MP3-encoded (rare but possible), it is copied out losslessly; otherwise it is re-encoded at high quality on your own hardware.
How it works
- Drop your file
Any common format, any size. Nothing is uploaded — the tool runs in your browser.
- Convert
Compatible files are repackaged instantly with zero quality loss; others are hardware-transcoded at high quality.
- Download
Your converted file is ready on your device — nothing to wait for, nothing to delete from a server.
Frequently asked questions
Does the length of the video matter?
No practical limit — a three-hour lecture recording works fine because nothing uploads. Extraction typically runs faster than the video's own duration.
What bitrate does the MP3 come out at?
High-quality encoding appropriate for music and speech. The output is a standard MP3 that plays on every device, player, and app made in the last twenty-five years.
Can I convert many MP4s at once?
Yes — select or drop several files together and they convert one after another on your device, each with its own download and a download-all button at the end.
Is my file uploaded to a server?
No. ConvertUno runs entirely in your browser on your own device. Your file never leaves your computer or phone — there is no upload at all.
Is it really free, with no watermark?
Yes. Processing happens on your device, so serving you costs us almost nothing — no watermark, no account, no file-size limit, no daily quota.