MP4 to MP3 converter
Pull the audio track out of an MP4 and save it as MP3, entirely in your browser. No upload, no conversion limit, no account.
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Accepts .mp4 · Up to 20 files at a time · up to 2.0 GB each "Upload" and "download" here mean your browser reading a file from this device and writing one back to it. Nothing is sent to a server — open your browser's network panel and watch: no request carries your file.
FAQ
Does the video get uploaded anywhere?
No. The conversion runs in a background thread inside your browser using a WebAssembly build of ffmpeg. You can confirm it by opening your browser's network panel before converting — there are no requests carrying your file.
Why is the MP3 lower quality than the original audio?
The audio inside an MP4 is normally AAC, which is already lossy. Re-encoding it to MP3 adds a second lossy pass. Raising the bitrate reduces the damage but cannot undo the first pass. There is no setting that avoids the second pass — every target format here is re-encoded, M4A included.
What bitrate should I pick?
192 kbps is the default and is transparent enough for speech and most music on ordinary playback equipment. Use 320 kbps if the source is high quality and the file size does not matter; drop to 128 kbps for voice recordings where size matters more than fidelity.
Can I convert several files at once?
Yes. Add up to twenty files and they convert one after another. They run sequentially rather than in parallel because each job needs its own slice of WebAssembly memory, and running them together would exhaust it.
Does it keep the title and artist tags?
Tags present in the source are carried over unless you switch on "Remove metadata". Note that most MP4 video files have no music tags to begin with, so there is often nothing to copy.
What happens to 5.1 surround audio?
MP3 has no surround mode that players reliably support, so multichannel audio is downmixed to stereo. You can force mono in the advanced options if you are converting speech and want a smaller file.
Is there a file size limit?
Yes, and it depends on the pair. Extracting audio throws the video away, so the output is small and the ceiling is the 2 GB we allow on desktop (512 MB on phones). Files over 64 MB are mounted rather than copied into the memory the converter works in, which is what makes multi-gigabyte inputs possible at all. The upload box on this page always states the real number.
Why does the first conversion take longer to start?
The ffmpeg WebAssembly core has to download before the first job. After that it stays in memory, so subsequent conversions start immediately.
Is it really free?
Yes — every conversion on this site, with no account, no watermark and no daily cap. The work happens on your own device, so there is no server bill for us to pass on to you.
Do I need to install anything?
No. It runs in any modern browser, on Windows, macOS, Linux, Android and iOS. There is nothing to download and nothing to sign up for, and once the page has loaded it keeps working with the network switched off.
Related converters
- MP3toMP4Wraps the audio in a video container over a black frame
- MP4toMOVRepackages the same streams — lossless and near-instant
- MP4toMKVRepackages the same streams — lossless and near-instant
- MP4toWebMRe-encodes every frame for the new container
- MP4toAVIRe-encodes every frame for the new container
- MP4toWAVDrops the video, keeps the audio losslessly as WAV
- MP4toAACDrops the video, re-encodes the audio to AAC
- MP4toFLACDrops the video, keeps the audio losslessly as FLAC