How to convert MP4 to MP3 (extract audio from any video)
Podcasts you recorded to video, YouTube-style tutorials you want to listen to on a walk, interview footage you need transcribed — extracting audio is a five-second job in the browser.
When you'd actually want this
Some genuinely useful reasons to pull audio out of a video:
- Podcasts recorded to video. Zoom/Meet/Teams recordings ship as MP4 but for audio-first distribution you want the MP3.
- Long lecture or tutorial videos you want to listen to while commuting or walking.
- Interview footage you need transcribed. Most transcription services accept MP3 and audio-only files are much cheaper to upload.
- Music videos. Extracting audio for personal use — same track, no video, tiny file.
- Voice memos accidentally recorded as video. Common iPhone mistake.
What "extract audio" actually does
An MP4 file is a container holding a video track and one or more audio tracks. The audio track inside a typical modern MP4 is already AAC (a compressed audio codec similar to MP3). "Extracting audio" means one of two things:
- Copying the AAC stream out into an M4A or AAC file, no re-encoding. Instant, lossless.
- Re-encoding the AAC to MP3 for compatibility with older players. Takes seconds, tiny quality drop.
Which one you want depends on where the audio is going. MP3 wins on compatibility — every player made in the last 25 years handles it. AAC/M4A wins on quality per byte, but not every hardware player supports it (older car stereos in particular).
Choose the right bitrate
For voice content (podcasts, interviews, lectures):
- 128 kbps MP3: plenty. Voice compresses well.
- 96 kbps MP3: still perfectly listenable, files ~25% smaller.
- 64 kbps MP3: acceptable for pure spoken word, noticeable artifacts on music.
For music:
- 192 kbps MP3: sweet spot for most people.
- 256 kbps MP3: audiophile-adjacent, effectively transparent.
- 320 kbps MP3: maximum MP3 quality, only worth it if you can tell the difference.
Don't bother with bitrates higher than the source. If the audio inside the MP4 is already 128 kbps AAC, exporting to 320 kbps MP3 wastes space without adding quality.
Doing it in the browser
Extract Audio from Video uses ffmpeg compiled to WebAssembly — the same engine used server-side by every audio-processing service, just running in your browser. Drop the video in, pick MP3 or WAV, choose bitrate, download. No upload, no queue.
Two things to know:
- Encoding is CPU-bound. A 1-hour video takes 30–90 seconds on a modern laptop. Not instant, but still faster than uploading a large video file.
- Battery matters. Plug in for anything over ~10 minutes of source video.
Common workflows after extracting
- Trim the intro and outro: MP3 Cutter lets you crop to a specific range without re-encoding.
- Convert MP3 to WAV for editing software that prefers uncompressed input: MP3 to WAV.
- Stitch multiple audio files into a single MP3: Audio Merger.
The privacy piece
Interviews, therapy sessions, personal voice notes, confidential meeting recordings — a lot of audio you'd want to extract from video is sensitive. Uploading it to a random converter site feels bad because it is bad; those files sit on strangers' servers for anywhere from an hour to a month.
Everything in this workflow — extract, trim, convert, merge — runs in your browser on DashConvert. Your source video and your extracted audio never leave your device.