What is this MP4 to MP3 converter?
A free, browser-based tool that extracts the audio track from a MP4 video and saves it as MP3. Add a file, preview it inline, and download the result. All processing happens locally in your browser, so your file is never uploaded and there is no watermark.
What happens to the video track when MP4 becomes MP3?
An MP4 from a phone, a screen recorder, or a Zoom export is mostly picture data: the video stream typically accounts for well over 95% of the bytes. Extracting to MP3 drops that stream entirely and keeps only the sound, which is why a few minutes of 4K weighing 500MB come out as a single-digit-MB audio file. The original video is not modified; you get a second, audio-only file alongside it.
That trade is exactly right for repurposing: publishing a webinar as a podcast episode, prepping an interview for transcription, or loading a conference talk onto a phone for the commute. None of those jobs need the picture, and every one of them gets easier once the file is a fraction of its former size.
Picking an MP3 bitrate for webinar and podcast material
MP4 audio is almost always AAC, which is already lossy, so encoding to MP3 stacks a second lossy generation on top. Keep the bitrate generous to make that stack inaudible: 192kbps handles speech cleanly, and 256kbps is the safer pick when music or applause matters. At 192kbps the output runs about 1.4MB per minute, so an hour-long recording lands near 85MB.
One practical note on inputs: an hour of heavily compressed meeting footage often stays within the roughly 200MB the browser handles comfortably, while high-bitrate 4K clips get there in a few minutes. Trim long takes down to the segment you need before converting.
How to use it
- Add a MP4 file on the left (drag & drop or click) — it shows an inline preview.
- Pick a quality preset (used only for lossy targets like MP3/M4A/OGG).
- Press “Convert & download” to get your MP3 file. The first run downloads the ~30MB converter once.
Lossy vs lossless audio
WAV and FLAC are lossless — they preserve the original waveform exactly (FLAC is compressed, WAV is not). MP3, M4A (AAC) and OGG are lossy: they shrink the file by discarding inaudible detail, and the quality preset controls the bitrate. Converting a lossy file to a lossless format can't recover quality that was already lost. One special case: converting to M4A when the source is already AAC just repackages the container (a lossless remux) — instant and bit-exact.
