Convert
Pull the audio out of an MP4
Extract the audio track from an MP4 video as an MP3 file at a chosen bitrate, locally in your browser.
For the best results: 192 kbps preserves music well; 128 kbps is plenty for talks and podcasts. The extraction re-encodes the audio track only, so even long videos finish quickly.
Advanced settingsoptional, defaults work well
Converted entirely in your browser, your files are never uploaded. Very large files depend on your device's memory.
What is MP4 to MP3?
MP4 to MP3 is a free file converter that pulls the audio track out of an MP4 video and saves it as an MP3 at the bitrate you choose, extracted locally in your browser. The audio is converted by an ffmpeg engine that runs inside your browser, so your recordings never leave your device. No upload, no queue, and no account, and once the engine has loaded it works even offline.
- ✦Runs entirely in your browser. Nothing you enter is ever uploaded
- ✦No account, no sign-up, and no data leaves your device
- ✦Works offline once the page has loaded
See it in action
A recorded webinar needs to become a podcast-style audio file for listening on a commute.
What you drop in
webinar.mp4, quality High (192 kbps)
What you get
webinar.mp3 with the full audio track: the 2-second test file produced an MP3 of exactly 2.0 seconds, nothing clipped at either end.
Tip: 192 kbps is transparent for speech; drop to 128 kbps for long recordings where size matters, or 320 kbps for music. The video stream is simply discarded, so even huge files extract quickly.
Use cases
What people use it for
Save the audio of a recorded uni lecture as an MP3 for revision during the commute.
Extract the soundtrack from a conference talk MP4 to listen back while exercising.
Pull the audio from a recorded family history interview so it plays on a basic MP3 player.
Who uses MP4 to MP3?
Commuting students
turn recorded lectures into podcast-style MP3s and reclaim travel time as revision time
Conference attendees
extract session recordings into audio they can absorb later without being glued to a screen
Genealogy researchers
convert filmed oral history interviews into audio files that archive services and older relatives can use
How it works
- 1Choose your files. They open in your browser, not on a server.
- 2Your device converts, compresses, or resizes them locally, with no upload.
- 3The converted files download straight back; nothing is kept anywhere.
Tips for the best results
- Use a low bitrate for speech-only recordings and reserve the higher settings for music.
- Confirm the video actually has audible sound before extracting, especially with screen captures.
- Extraction is faster than video conversion, since only the thin audio stream is processed.
- Name extracted files by topic and date immediately, before a folder of identical names accumulates.
- For a spoken lecture, the resulting MP3 will be a small fraction of the video's size.
FAQ
Frequently asked questions
How does the tool get MP3 audio out of an MP4?
An MP4 is a container with the picture and sound stored as separate streams inside. The extractor opens the container, reads only the audio stream, which is usually AAC, and re-encodes it as an MP3 at the bitrate you pick. The video stream is skipped entirely, which is why the result is a small, purely listenable file.
Which bitrate should I pick for the extracted MP3?
Let the content choose. Lectures, talks, and interviews are almost entirely speech, which compresses gracefully at the lower settings. Anything with music worth hearing properly deserves a higher bitrate, since instruments occupy far more of the frequency spectrum than voices do. When in doubt, extract a short test file at two settings and listen on your usual headphones.
Does going from AAC to MP3 lose quality?
A little, because both codecs are lossy and re-encoding means the MP3 encoder makes fresh approximations of audio that AAC had already approximated once. For spoken material the difference is inaudible at sensible bitrates. Choosing an MP3 bitrate at or above the quality of the source track keeps the generational loss below what ears detect.
Is the video watched or stored by anyone during extraction?
No one and nowhere. The MP4 is opened inside your own browser by ffmpeg running as WebAssembly, and only the finished MP3 ever leaves the tab, as a download to your own disk. A recorded therapy session or confidential briefing has no server-side existence at any point, because no server participates in the work.
Why is the MP3 so much smaller than the video was?
Because the picture was doing most of the eating. Video data typically accounts for the overwhelming majority of an MP4's size, with the soundtrack a thin slice alongside it. Discard the frames and you keep only that slice, re-encoded to MP3. An hour of video can collapse to a file that emails comfortably.
How do I convert MP4 to MP3 on my phone?
The page works in a mobile browser: open it, select the MP4 from your files, choose a bitrate, and save the MP3 it produces. Phones have less memory than computers, so very long videos are better handled on a laptop. Short and medium recordings extract on a phone without trouble.
Why did my MP4 produce no MP3?
The most common cause is a video with no audio stream at all, such as a screen capture recorded without a microphone. Play the file first and confirm you can hear something. A rarer cause is an unusual audio codec inside the container, which some obscure recording software produces.
Does extracting audio from a video work offline?
Once the engine is cached, yes. Your first visit fetches the WebAssembly build of ffmpeg, around 31 MB, and the browser keeps it. After that the page extracts audio with the connection off entirely, which suits travel and workplaces where uploads to random websites are blocked anyway.
Are there any usage limits?
None. Everything is generated locally in your browser, so there is no server cost, no metering, and no daily cap, use it as many times as you like, completely free.
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