Convert MP4 to MP3
Your files are processed on your device. We never upload them.
Video is read and written with Mediabunny, under the Mozilla Public License. MP3 files are made with the LAME encoder, under the GNU LGPL.
How to convert MP4 to MP3
- 01A ▸Choose your MP4 videos, or drop them on the page. Several at once is fine.
- 02A ▸Select Save the sound as MP3.
- 03A ▸Download each MP3.
About MP4 to MP3
Where MP4 files come from
MP4 videos from phones, screen recordings, lectures, and podcasts' video versions carry their sound as AAC. Many people want just the sound, as an MP3, for music players, car stereos, voice notes, and transcription apps that ask for MP3.
What changes
- The picture is left out; only the main sound track is kept.
- The sound is decoded and encoded again as MP3 with the LAME encoder, at a high quality setting. Stereo stays stereo, and the sample rate stays the same where MP3 allows it.
- Titles and other details stored in the video are not carried over.
Measured
Our one-minute 1080p sample at 30 frames a second with stereo AAC sound (a synthetic test pattern, which is easier to encode than real footage), converted in Chrome on a laptop. Phone timings are still to be measured.
| MP4 file | 61.1 MB |
|---|---|
| MP3 file | 2.4 MB |
| Time (Chrome, laptop) | 0.8 seconds, including loading the MP3 encoder |
| M4A instead (Extract audio) | 1.4 MB in 0.2 seconds, sound copied as it is |
| Time on phones | still to be measured |
In your browser
Decoding the sound needs WebCodecs audio, found in Chrome, Edge, and Firefox, and in Safari from version 26. No browser encodes MP3 itself, so the first conversion loads a 120 KB MP3 encoder (LAME, compiled to WebAssembly); later conversions reuse it from the browser's cache.
Limits
- Videos with surround sound in AC-3 or DTS can't be converted to MP3 here yet.
- MP3 holds at most two channels, so surround sound would be mixed down to stereo.
Other options
- Extract audio as M4A: copies the sound exactly as it is, in seconds.
- Trim video: shorten the video first to keep only part of the sound.
Questions
Are my videos uploaded?
No. Your files are processed on your device. We never upload them.
What quality is the MP3?
A high-quality setting suited to music and speech. The sound inside an MP4 is already compressed (AAC), so converting makes a new copy; the difference is hard to hear.
Is there a faster way that keeps the exact sound?
Yes. Extract audio as M4A copies the sound as it is, in seconds. M4A plays on iPhones, Macs, Android, and Windows; choose MP3 for old players and car stereos.
Can I convert other video formats to MP3?
Yes. MOV, M4V, MKV, and WebM videos work here too.
Why doesn't it work in my browser?
Converting to MP3 decodes the sound first, which needs WebCodecs audio. Chrome, Edge, and Firefox have it; Safari has it from version 26.