MP4 to MP3 Converter
Pull the audio out of any video — as MP3, WAV, or the original track untouched. Nothing uploads.
Runs entirely in your browser. Your videos never leave this device.
This tool converts a video to MP3 on your own device — the file never uploads. Drop an MP4, MOV, WebM or MKV, choose a bitrate, and only the audio is decoded and re-encoded; the video stream is skipped entirely, which is why even long recordings finish far faster than they play. If you’d rather not re-encode at all, Original copies the audio stream out byte-for-byte — from an MP4 or iPhone MOV that is almost always AAC, saved as .m4a — and WAV gives you uncompressed PCM for editing. Because the MP3 runs at a fixed bitrate, its size is known before you start: bitrate × duration, shown next to each option. No watermark, no account, no file-size cap.
How do I convert MP4 to MP3 without uploading the video?
Use a converter that runs inside the browser instead of on a server. This page loads FFmpeg compiled to WebAssembly and processes your file locally: the container is opened, the audio track is decoded and re-encoded with the LAME MP3 encoder, and the video stream is never even decoded — that’s why it runs far faster than real time, and why the network tab shows no request carrying your video. One thing most converters don’t tell you: the audio inside an MP4 or MOV is already compressed (almost always AAC), so converting it to MP3 compresses it a second time. If the file only needs to play on a phone, tablet or computer, choose Original instead — it copies the AAC track out untouched as an .m4a, with zero added loss and usually a smaller file than a 192 kbps MP3. Pick MP3 when the audio must play on absolutely everything, and 320 kbps if you want the re-encode to cost as little as possible.
The facts that matter
| Output formats | MP3 at 128, 192 or 320 kbps (constant bitrate), WAV (16-bit PCM), or the original stream copied losslessly: .m4a for AAC/ALAC, .ogg for Opus/Vorbis, .flac, .wav for PCM |
|---|---|
| Input | MP4, MOV, M4V, WebM, MKV, AVI, 3GP and anything else FFmpeg reads — audio-only files (M4A, WAV, FLAC, OGG) convert too |
| Quality | MP3 is lossy and can’t exceed the source; 192 kbps is transparent for most listeners. Original mode is lossless — the exact bytes the video carried |
| Speed | Only the audio is decoded, so it runs far faster than real time — measured at about 100× on a laptop: two minutes of 1080p video became an MP3 in under two seconds, and an hour of audio takes well under a minute. Phones are slower |
| Size | MP3 ≈ 0.96 MB/min at 128 kbps, 1.4 MB/min at 192, 2.4 MB/min at 320. WAV ≈ 10–11.5 MB/min (44.1–48 kHz stereo). The estimate is shown before you convert |
| Tracks and channels | The first audio track is extracted and the result says if there were more. Surround (5.1/7.1) is downmixed to stereo for MP3 and kept as-is for WAV |
| Limits | No watermark, no signup, no artificial size cap — browser memory (~1–2 GB) is the practical ceiling |
| Privacy | Processed entirely on your device — the video never leaves it |
Get a better result
- Choose Original when the audio only has to play on your phone, tablet or computer: an MP4 or MOV almost always carries AAC, and the .m4a you get is the very same audio with no re-encoding loss — usually smaller than a 192 kbps MP3, and it plays natively on iPhone, Android, Mac and Windows. Choose MP3 when the file has to work on absolutely everything, including older car stereos and editors that reject M4A.
- Match the bitrate to the content. Speech — lectures, meetings, interviews, voice notes — is perfectly clear at 128 kbps, and an hour lands under 60 MB. Music is worth 192 kbps. 320 kbps doesn’t add quality the video never had; it only minimises the loss of the re-encode, so use it when the source audio was itself high-bitrate or when you’ll edit the MP3 again later.
- Going into an editor? Pick WAV. It is uncompressed, so the next export doesn’t stack a third round of lossy compression on top — at the cost of roughly 10 MB per minute. Most editors also open the .m4a from Original directly.
- Only need a stretch of it — one answer from a two-hour meeting, one song from a set? Cut the range with the trim tool first (lossless, done in seconds), then convert the short clip here. The size estimate scales with the duration: a 3-minute excerpt at 192 kbps is about 4 MB.
- Screen recordings with a separate microphone track, or films with several languages: this tool extracts the first audio track and tells you how many it found. Surround sound is folded down to stereo for MP3 — WAV keeps every channel, which also makes a 5.1 file three times larger than stereo.
Frequently asked questions
Is my video uploaded to a server?
No. The engine (FFmpeg compiled to WebAssembly) downloads once into your browser, and the conversion runs on your device. You can verify it: open the browser’s network tab while converting — after the engine loads, no request carries your video. Once the engine is cached, the page even works offline.
Does converting MP4 to MP3 lose quality?
Yes, a little — MP3 is a lossy format, and the audio inside the video was already lossy (AAC in nearly every MP4 and MOV), so this is a second compression. At 192 kbps the extra loss is inaudible for most people on most material; at 320 kbps it is as small as MP3 allows; at 128 kbps it is audible on music but fine for speech. If you want zero loss, use Original: it copies the existing track out unchanged.
MP3, M4A or WAV — which should I pick?
MP3 plays on virtually everything ever made and is the safe choice for sharing. M4A — what Original gives you from an MP4 or MOV — is the video’s own AAC track copied without re-encoding: the same quality as the video, usually a smaller file than an equivalent MP3, and it plays natively on iPhone, Android, Mac, Windows and every browser; only some older devices and a few editors reject it. WAV is uncompressed PCM: the right input for editing, and about 10 MB per minute.
Which MP3 bitrate should I choose?
128 kbps for speech — podcasts, lectures, meetings — at about 1 MB per minute. 192 kbps as the default for music and mixed content, about 1.4 MB per minute. 320 kbps when you want the smallest possible loss or plan to edit the file again, at 2.4 MB per minute. A higher bitrate can’t restore detail the source never had.
How big will the file be?
For MP3 it is fixed: bitrate × duration. A 10-minute video at 192 kbps becomes a 14.4 MB MP3 — within half a percent, the rest being the ID3 tag and encoder header. The tool shows this estimate next to each bitrate before you start. WAV is sample rate × channels × 2 bytes per second: 48 kHz stereo is 11.5 MB per minute. Original is exactly the size of the audio track inside the video, typically 1–2 MB per minute for AAC.
How long does it take?
Much less than the video’s length. Only the audio stream is decoded and encoded — the video is skipped — so the encoder runs about 100 times faster than real time on a laptop (measured: a two-minute 1080p file of 187 MB became an MP3 in 1.9 seconds; an hour of audio takes well under a minute). Phones and older machines are slower, and the tool shows live progress with a time estimate. Original mode is faster still, since nothing is decoded — the track is copied out. The first visit also downloads the 32 MB engine once; it is cached afterwards.
Which video formats can I convert?
Anything FFmpeg can read: MP4, MOV (including iPhone HEVC), M4V, WebM, MKV, AVI, 3GP, MTS, WMV, FLV and more. Your browser may not be able to preview some of them (AVI, WMV, MTS) — the conversion still works, it just runs without a player. Audio files work too: drop an M4A, WAV, FLAC or OGG to turn it into an MP3.
My video has several audio tracks — which one do I get?
The first one, in the order the file lists them — for a screen recording that is usually the system audio, for a film the main language. The result tells you how many tracks the file had and the language tag of the one extracted, if the file carried one. Choosing a different track needs a desktop tool for now.
Why did Original give me .ogg or .wav instead of .m4a?
Because the format follows the codec that was inside your video. AAC and ALAC become .m4a, MP3 becomes .mp3, Opus and Vorbis (typical of WebM screen recordings) become .ogg, FLAC stays .flac, and uncompressed PCM (some cameras record it) becomes .wav. All of these are the original bytes, untouched. AC-3, E-AC-3 and DTS — surround tracks from disc rips — have no standalone format a browser or phone can play, so for those the tool converts to MP3 at 320 kbps and labels the result.