MP4 to MP3
Drop an MP4 (or several). We pull the audio track and re-encode it as MP3 right here in your tab. No upload, no signup, no queue. The video never leaves your device.
drop your MP4 here
or click to pick. We accept MP4, MOV, WebM, MKV too.
How it works
An MP4 is a container, not a format. Inside it sit separate streams — a video track, one or more audio tracks, sometimes subtitles and chapter markers — and the audio is almost always AAC. Pulling the sound out means reading the container, discarding the picture, and re-encoding that audio stream as MP3.
That happens here with a WebAssembly build of FFmpeg running inside the page. The first conversion downloads it, which is a genuine 32 MB and takes a few seconds on a good connection; the progress bar shows the byte count so you can see it moving. After that it is stored on your device and every later conversion starts immediately, including on your next visit.
What you actually lose
AAC to MP3 is a lossy-to-lossy conversion, so the encoder is working from audio that has already had material discarded once and throws away more. On speech this is inaudible. On music you can sometimes hear it in cymbals, applause and reverb tails — the parts that are noise-like and expensive to encode.
The practical consequence is that a higher bitrate cannot recover what the MP4 never had. If the video's audio track is 128 kbps AAC, exporting a 320 kbps MP3 gives you a bigger file containing the same information, not a better one. Matching or slightly exceeding the source is the sensible move, and if you do not know what the source is, 192 is a safe default.
Which bitrate to pick
- 128 kbps — lectures, interviews, podcasts, anything that is one person talking. Speech has a narrow bandwidth and this is genuinely enough; the file is about half the size of the alternative, which matters if you are emailing it or loading a phone.
- 192 kbps — the default, and correct when you do not know what the source was. Fine for music you are listening to casually.
- 256 or 320 kbps — worth it when the MP4 came from a high-quality master: a music video, a concert recording, a film with a proper mix. Above 320 there is nothing to gain; that is the format ceiling.
Where these files usually come from
Most MP4s that land here are one of a handful of things, and each has a sensible setting. A Zoom or Teams recording is speech at a modest bitrate, so 128 and nothing higher. A screen recording from OBS or QuickTime is usually 48 kHz AAC and converts cleanly. iPhone and GoPro footage arrives as MOV rather than MP4 but goes through the same tool. A DSLR clip may carry uncompressed PCM audio inside the MP4, in which case you are converting from a lossless source and 256 or 320 is genuinely worth choosing.
If the video is a lecture or an interview you plan to transcribe rather than listen to, prep it for Whisper instead: transcription models want 16 kHz mono, which is a much smaller file and produces the same text.
Multiple audio tracks
Some MP4s carry more than one audio stream — a film with several languages, a screen recording that captured system audio and a microphone separately, a DaVinci Resolve export with stems left in. This tool takes the first track and ignores the rest, because there is no reliable way to label them in a browser. If the first track is not the one you wanted, the file needs a desktop tool that can list streams, such as FFmpeg itself or VLC.
When MP3 is the wrong output
If the audio is going into an editor — Audacity, Reaper, Premiere, Logic — take the audio extractor and choose WAV instead. Editing an MP3 and re-exporting it means a third lossy generation, and WAV costs you nothing but disk space. MP3 is the right answer when a person is going to listen to the file, and the wrong one when a program is going to process it.
MOV, WebM and MKV
The same tool handles them. An iPhone .mov, a screen capture saved as .webm, an .mkv from a desktop recorder — all read the same way, because the container differs but the audio inside is still AAC, Opus or PCM. There is a dedicated MOV page if that is what you arrived with, but it runs the same code.
Size, memory and phones
Around 500 MB is the practical ceiling, and it is memory rather than time that stops you. The audio is decoded to raw samples before it is re-encoded, and those samples sit in RAM uncompressed. A phone gives up sooner than a laptop, and Safari on iOS sooner than Chrome on Android, because iOS caps how much memory a single tab may use. A two-hour 1080p recording is usually fine, since only the audio stream is decoded; a very long 4K file may not be. If one fails, cut it into pieces first.
FAQ
Is this MP4 to MP3 converter free?
Yes. No signup, no daily limit, no watermark, no ads.
Does my video get uploaded to a server?
No. The conversion runs in your browser tab. Load the page, switch to airplane mode, then drop a file — it still works. That is the test, and it is the whole point of the site.
Can I convert multiple files at once?
Yes. Drop several videos and you get them all back as a zip of MP3s.
What is the maximum file size?
Around 500 MB on a typical laptop. It is memory that stops you rather than time, so phones give up sooner than laptops and iPhones soonest of all. Only the audio stream is decoded, so a long 1080p recording is usually fine.
Why does the first conversion take a few seconds?
It downloads a 32 MB WebAssembly build of FFmpeg the first time you use it. The progress bar shows the byte count. After that it is stored on your device and later conversions start immediately, including on your next visit.
Which bitrate should I choose?
128 for speech, 192 if you are not sure, 256 or 320 only when the video's own audio was high quality to begin with. A higher bitrate cannot add detail the MP4 never contained.
Will 320 kbps make my video's audio sound better?
No. It makes a larger file with the same information in it. The audio inside an MP4 is usually AAC that has already been compressed once, and the MP3 encoder cannot recover what was discarded then.
My video has two audio tracks. Which one do I get?
The first one. Browsers give no reliable way to label the others, so if you need a specific language or a separate microphone track, that needs a desktop tool like VLC or FFmpeg.
Can I get the audio as WAV instead?
Yes, through the audio extractor. Choose WAV whenever the file is going into an editor, since editing an MP3 and re-exporting adds another generation of loss.
Does it work with MOV, WebM and MKV?
Yes, in this same tool. The container differs but the audio inside is still AAC, Opus or PCM.
Can it convert a DRM-protected video?
No. Purchased films and anything from a streaming service are encrypted, and we cannot decrypt them.