MP4 to MP3 Converter (Free, Online, No Upload)

Pull the audio out of any MP4 video and save it as an MP3. The conversion runs right in your browser, so your files never get uploaded anywhere. Completely free, no account required.

Try it in your browser

Loading FFmpeg engine... (~31 MB)

How to mp4 to mp3 converter online

1Drop your MP4 file into the tool above, or click to browse your files.
2Pick a bitrate preset or adjust quality settings to your preference.
3Click convert and download your MP3 file when it's ready.

About MP3 format

MP4 is the most common video format. It stores video, audio, and sometimes subtitles in a single file. MP3 is the standard for compressed audio, and practically every device and app can play it.

Extracting audio from video is useful in a lot of situations. Podcasters record on video and then pull the audio for publishing. Students grab lectures. Musicians isolate a track they want to practice with. Sometimes you just want the audio from a music video without the visuals taking up space.

During conversion, the video stream gets discarded entirely. The audio stream is re-encoded as MP3 at the bitrate you choose. Higher bitrates (like 320kbps) sound better but produce bigger files. Lower bitrates (128kbps) save space and still sound fine for speech or casual listening.

Use the API

curl -X POST https://renderio.dev/api/v1/run-ffmpeg-command \
  -H "X-API-KEY: ffsk_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
  "ffmpeg_command": "-i {{in_video}} -vn -c:a libmp3lame -q:a 2 {{out_audio}}",
  "input_files": {
    "in_video": "https://example.com/input.mp4"
  },
  "output_files": {
    "out_audio": "output.mp3"
  }
}'

Need an API key? Get your free API key to start processing files programmatically.

Common Variations

320kbps constant bitrate

-i input.mp4 -vn -c:a libmp3lame -b:a 320k output.mp3

128kbps for smaller file size

-i input.mp4 -vn -c:a libmp3lame -b:a 128k output.mp3

Extract a specific time range

-i input.mp4 -ss 00:01:00 -t 00:02:00 -vn -c:a libmp3lame -q:a 2 output.mp3

Mono output for speech or podcasts

-i input.mp4 -vn -ac 1 -c:a libmp3lame -q:a 4 output.mp3

Frequently Asked Questions

Is this MP4 to MP3 converter really free?+

Yes, completely free. No account, no trial period, no limits on how many files you convert. Just open the page and go.

Are my files safe? Do you upload anything?+

Your files never leave your device. The conversion happens locally in your browser. Nothing gets sent to a server, and nothing is stored.

What's the maximum file size?+

There's no server-side limit because your files stay on your device. The only constraint is your device's available memory. Most phones and laptops handle files up to a few hundred MB without issues.

Does this work on iPhone or Android?+

Yes. It works in any modern browser on any device. Chrome, Firefox, Safari, Edge on desktop or mobile.

Can I choose the audio bitrate?+

Yes. You can pick from common presets like 320kbps, 192kbps, or 128kbps depending on whether you want higher quality or a smaller file.

Can I extract just part of the audio?+

Yes. Set a start time and end time to grab a specific section. Useful if you only need a clip from a longer video.

What if my MP4 has no audio track?+

The tool will tell you. You need a video file that actually contains an audio stream for the conversion to work.

How is this different from other converters?+

Most MP4 to MP3 converters upload your file to their server, process it there, and send it back. This one does the entire conversion in your browser. Your files stay on your machine the whole time.

Privacy

Your files never leave your device. The entire conversion runs locally in your browser. No data gets uploaded to any server, and nothing is stored or tracked.

Related Operations

Need to process at scale?

Automate this with the RenderIO FFmpeg API. Process thousands of files programmatically or through no-code video automation.

Get your API key