MP4 to MP3 Converter
Extract the audio track from MP4, WebM, or MOV videos directly in your browser. Lossless WAV output (renames to .mp3 if needed). No upload, no signup.
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About MP4 to MP3 Converter
Convert MP4 to MP3 free online — directly in your browser. No upload, no signup, no waiting. Paste your MP4, get MP3 instantly.
MP4 to MP3 Converter extracts the audio track from any MP4, WebM, or MOV video right in your browser. Drop in a video file, click Extract, and download the audio as a lossless WAV file. Optionally rename the download to .mp3 — most apps (DAWs, video editors, podcast tools, messaging clients, even Spotify uploaders) read both formats interchangeably from the file's actual codec metadata rather than the extension. The common workflow: you have a podcast recorded straight into Zoom, an interview captured on a phone, a webinar saved as MP4, or a long YouTube video downloaded for offline listening — and you want just the audio. Maybe to listen during a commute, edit in Audacity, transcribe with Whisper, or extract a sample. Uploading to a third-party converter site is slow, leaks the audio, and often hides a watermark behind a sign-up wall. This tool runs entirely in your browser using the Web Audio API, so the file never leaves your device. Output is delivered as WAV (uncompressed, lossless, every device supports it) because the browser cannot encode true MP3 codec locally without a 250KB+ external library. For most use cases this is actually better: WAV is lossless, so when you import the file into a DAW, podcast editor, or transcription tool, you start from the cleanest possible source. If you genuinely need MP3 codec (smaller file size for upload limits, MP3-only legacy players), run the extracted WAV through FFmpeg, Audacity, or any desktop converter as a final step — that takes 5 seconds and gives you precise control over bitrate and channels. The tool surfaces useful metadata after extraction: original duration, channel count (mono vs stereo), and sample rate. This helps you decide whether the audio needs further cleanup before final use. For example, a 48 kHz mono recording from a phone may want resampling to 44.1 kHz stereo before publishing as a podcast episode. Supported sources: any video container whose audio codec is supported by your browser's Web Audio API. That includes MP4 (AAC), WebM (Opus or Vorbis), MOV (AAC), and some MKV variants. If decoding fails, the error message will say so — usually the fix is to re-export the source video as a standard MP4 first.
Key features
- Lossless audio extraction. Decodes the original audio track via Web Audio API and re-encodes as uncompressed WAV. No quality loss versus the source.
- Runs entirely in your browser. Web Audio API does the decoding locally. Your video never leaves your device — no upload, no server, no account.
- Works with MP4, WebM, MOV. Any video container whose audio codec the browser can decode. AAC, Opus, Vorbis are all covered by modern browsers.
- Audio metadata surfaced. Shows duration, channel count (mono / stereo), and sample rate so you can decide whether further processing is needed.
- Rename to .mp3 with one click. Most DAWs, podcast tools, and messaging apps accept WAV under the .mp3 extension. If you specifically need MP3 codec, use FFmpeg afterward.
Common use cases
- Pull audio from a Zoom or Google Meet recording. Extract the call audio for transcription, sharing as a podcast episode, or archiving without the video overhead.
- Get the audio from a downloaded YouTube video. Convert long videos to listen-only format for commute or offline playback without re-downloading from YouTube.
- Extract clean audio for transcription with Whisper or similar. Feed AI transcription tools with the WAV file — usually faster and more accurate than letting them process the full video.
- Isolate audio for a podcast or sound design project. Pull the audio track into your DAW (Audacity, Logic, Ableton, Reaper) for editing, EQ, and mixing.
- Convert lecture or webinar recordings. Many educational videos are too large to share. Audio-only versions reduce file size by 80-90% and remain understandable.
How to use it
- Choose your video file — MP4, WebM, or MOV — basically any video format your browser can play. There is no hard size limit but very large files may hit memory caps.
- Click 'Extract audio' — The tool reads the video as an ArrayBuffer, decodes the audio track with Web Audio API, then encodes the result as WAV. Takes a few seconds for short files, longer for long ones.
- Review metadata and preview — Confirm duration, channels, and sample rate look right. Play the inline audio preview to verify.
- Download as .wav or rename to .mp3 — WAV is the actual lossless audio. The .mp3 button delivers the same data with an .mp3 extension for tools that filter by file type.
- Optional: convert to true MP3 with a desktop tool — Drop the WAV into FFmpeg, Audacity, or any DAW and export as MP3 with your preferred bitrate (typically 128 / 192 / 320 kbps).
Examples
Podcast recorded in Zoom
Input interview-2026-05.mp4 (45 min, 320 MB)
Output interview-2026-05.wav (~450 MB, lossless audio at original sample rate)
YouTube download for offline listening
Input lecture-week-3.mp4 (60 min)
Output lecture-week-3.wav — feed to your podcast app or audio player
Music video to album track
Input single-music-video.mp4
Output single-music-video.wav — drop into DAW for sampling or playlist building
Troubleshooting
'Could not decode this video's audio'
Cause Your browser cannot decode the audio codec inside the video container. Common with older MKV files, niche codecs, or DRM-protected videos.
Fix Re-export the source video as a standard MP4 (H.264 + AAC) using FFmpeg, HandBrake, or any video editor. Then retry the extraction.
Output file is huge (hundreds of MB)
Cause WAV is uncompressed — about 10 MB per minute at CD quality. A 1-hour video produces a ~600 MB WAV.
Fix If you need a smaller file, run the WAV through FFmpeg with `-codec:a libmp3lame -b:a 128k` to get a typical 5-10x size reduction.
Browser crashes or runs out of memory on large files
Cause Web Audio API loads the entire decoded buffer into memory. Files over ~1 hour at high sample rates can exceed browser memory limits.
Fix Trim the video first (free with FFmpeg: `ffmpeg -i in.mp4 -ss 0 -t 1800 -c copy half.mp4`) or use a desktop converter for very long files.
Audio sounds different from the video
Cause Extremely rare — usually means the video's audio codec uses a non-standard sample rate that gets resampled during decode.
Fix Confirm the sample rate in the metadata. If it does not match the original (44.1 kHz or 48 kHz are standard), resample with Audacity or FFmpeg.
FAQ · 05
Is my video uploaded to a server?
No. The entire extraction runs in your browser using the Web Audio API. Your video file and the extracted audio never leave your device. Closing the tab discards everything.
Why is the output WAV instead of MP3?
Browsers cannot encode the MP3 codec locally without a 250KB+ external library. WAV is uncompressed and universally supported — for most use cases (transcription, podcast editing, DAW import) this is actually preferable because it is lossless. For true MP3 codec, run the WAV through FFmpeg or Audacity afterward.
Will video editors accept the .mp3 renamed WAV?
Almost always yes. Tools like Audacity, Logic, Ableton, Premiere, DaVinci Resolve, Audition, Reaper, Pro Tools, and even WhatsApp/Telegram read the actual file contents rather than trusting the extension. The exception is some legacy or strict tools that filter by extension only — for those, keep the .wav extension.
Is there a file size limit?
No hard limit from the tool. The practical limit is your browser's memory. Most modern browsers handle 1-2 hour videos at standard quality. Very long files (3+ hours) may run out of memory.
Does this work with WebM, MOV, or MKV?
WebM and MOV: yes, as long as your browser supports the audio codec inside (Opus, Vorbis, AAC all work). MKV: depends on the container's audio codec — most fail and need conversion to MP4 first.
Scenario examples
Practical input/output workflows for this tool live on a dedicated examples page.
Working in media tools? You may also need Image To PDF, Image Resizer or PNG to JPG Converter — part of our media tools toolkit.
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