Extract the audio from an MP4 video as MP3
Drop your MP4 (or MOV, WebM) video, choose a bitrate (192 kbps suits music, 96 kbps suits speech), and click Convert: the soundtrack is decoded and encoded as MP3 right in your browser. You can play it before downloading. The video is never uploaded to a server.
- ✅ Free
- 🔒 No sign-up
- 📱 Works on mobile
- ⚡ Instant results
🔒 Everything runs in your browser. Your data and files never leave your device.
How a video becomes an MP3
Your browser opens the file, decodes the audio track into raw samples (digital sound), and the MP3 encoder compresses them at the quality you chose. The picture is ignored: only the soundtrack is used.
\[ \text{MP3 size (bytes)} = \dfrac{\text{length in seconds} \times \text{bitrate in kbps} \times 1{,}000}{8} \]
| Bitrate | Size per minute | Best for |
|---|---|---|
| 96 kbps | 0.7 MB | Speech, lectures, meetings |
| 128 kbps | 0.9 MB | Podcasts, everyday use |
| 192 kbps | 1.4 MB | Music, good balance |
| 256 kbps | 1.8 MB | Music, careful listening |
| 320 kbps | 2.3 MB | Highest MP3 quality |
Supported formats and limits
Which files open depends on your browser: MP4 (H.264 + AAC), MOV, WebM, M4A, WAV, and OGG work in recent browsers. A file with no audio track or with a rare codec (some MKV files, AC3) is rejected with a message.
- Size: 500 MB maximum. The sound is decoded in memory: one hour of stereo takes about 600 MB of RAM, so use a computer for long videos.
- Quality: MP3 is a lossy format. Converting already-compressed sound (AAC) adds a little more loss, so stay at 192 kbps or above for music.
- Rights: only extract content you have the right to copy.
3 real-life examples
A 1-hour recorded lecture
You pull the voice from a lecture video at 96 kbps mono: \( \dfrac{3{,}600 \, \text{s} \times 96 \times 1{,}000}{8} = 43.2 \) million bytes, about 41 MB. You can listen on your commute without streaming any video.
A 4-minute music video
At 192 kbps, \( \dfrac{240 \, \text{s} \times 192 \times 1{,}000}{8} = 5.76 \) million bytes, about 5.5 MB. At 128 kbps the file would be 3.7 MB.
A 45-minute video podcast
At 128 kbps: \( \dfrac{2{,}700 \, \text{s} \times 128 \times 1{,}000}{8} = 43.2 \) million bytes, or 41 MB. Mono mode doesn't change the size at the same bitrate: lower the bitrate instead for speech.