Convert MP4 to MP3

When the sound is the part you actually want

A surprising amount of audio arrives wrapped in video it never needed. A recorded lecture where the slides add nothing, a talk you want on your phone for the commute, a voice memo someone insisted on sending as a video, a song from your own rehearsal footage you want to practise against — in every case the picture is dead weight. Extracting the track turns a file of hundreds of megabytes into a few that play in any music app, queue in a podcast player and attach to an e-mail without complaint. Because the browser does the decoding on your own device, the file also never leaves your hands — worth remembering when the recording is a meeting or an interview rather than something public.

Bitrate, in plain words

Bitrate is simply how many bits each second of sound is allowed to use — more bits, more fidelity, bigger file. For speech, 128 kbps is comfortably enough; voices carry far less detail than music and the smaller file is genuinely nicer to store and send. 192 kbps is the safe everyday choice that virtually nobody can tell from the original. 320 kbps is for music you care about keeping. One honest caveat: the bitrate sets a ceiling, not a promise. If the video's own audio track was compressed to begin with — and most are — converting it at 320 kbps faithfully preserves that quality but cannot add detail that was never recorded. Picking a high bitrate never hurts; expecting it to improve the source will disappoint. When in doubt, 192 kbps is the answer — it is the setting that is never noticeably wrong in either direction.

The two limits, and why they are different kinds of limit

Free conversions cover files up to 1.5 minutes and 20 MB — a fence, lifted by a day pass or unlock. Behind it sits a second, technical ceiling of around 45 minutes that no payment moves, because the decoded audio exists briefly as uncompressed samples in your device's memory, and forty-five minutes of stereo sound is already well over 400 MB of raw data. On a phone or an older laptop the practical ceiling may sit a little lower still — the browser gives up when memory runs out, not at a tidy round number. For a full concert recording or a feature-length soundtrack, a desktop application with proper streaming is honestly the better tool, and we would rather say so than watch your tab fall over at the 90 per cent mark.

Whose audio is it — and what to do with it next

The comfortable ground is your own material: your recordings, your lectures with permission, voice messages sent to you, content you hold the rights to. Extracting music from other people's videos to build a free music library is the use case every platform's terms prohibit and copyright law frowns on — the tool cannot tell the difference, so that judgement stays with you, and we would rather name it than pretend the question does not exist. Once the MP3 is on your device, it rarely needs to stay exactly as extracted: /audio-volume-editor opens it on a waveform where you can dim the shuffling before the talk starts, mute a cough or an interruption mid-recording, and download the tidied version — a two-minute polish that makes an extracted track feel deliberately produced.

How this works without uploading anything

Your browser already contains the decoders needed to play the video — this tool simply asks it to decode the audio track, then re-encodes that sound as MP3 with JavaScript, all on your own device. That's also why it's fast: no upload, no queue, no server.