MP4 to MP3
Pull the soundtrack out of any video and save it as an MP3, privately on your device.
Your files never leave your device
or drop an MP4, MOV, WebM or M4A file here
MP4, MOV, M4A, WebM and more · up to about 500 MB
Want the song from a music video, the audio of a lecture, or a voice memo that your phone saved as a video? This free MP4 to MP3 converter extracts the sound from a video file and saves it as a standard MP3. It plays on every phone, car stereo and media player. The whole conversion happens in your browser, so your video is never uploaded.
Your files never leave your device. This MP4 to MP3 tool runs 100% in your browser. There are no uploads, no accounts and no watermarks, and there is no tracking inside the tool.
How to convert MP4 to MP3
- Choose your video. Click Select video or drop an MP4 (or MOV, M4A, WebM) onto the box. The file stays on your device; only its length is read.
- Pick the MP3 quality. Choose 128, 192 or 320 kbps, and Stereo or Mono. Optionally enter start and end times to keep just part of the audio. An estimated file size is shown.
- Convert. Press Convert to MP3. The audio is decoded by your browser and encoded to MP3 with a progress bar. Long videos can take a minute or two.
- Listen and download. Play the result in the built-in player to check it, then tap Download MP3.
Features
Why convert in the browser?
Typical online converters make you upload the entire video, often hundreds of megabytes, wait in a queue, and then download the result. That is slow on mobile data, and it means a copy of your file sits on someone else’s computer. This converter flips the process. The web page loads a compact MP3 encoder, and your own device does the work. Your browser’s audio engine (the Web Audio API) decodes the soundtrack, and the open-source lamejs encoder turns it into MP3 frames. The finished file goes straight to your downloads. Nothing about your video is sent to WorldScope.
Choosing a bitrate: quality vs size
MP3 bitrate is the amount of data used for each second of sound. More data keeps more detail, especially in cymbals, reverb and other high-frequency sounds, but makes the file larger. Because this tool writes constant-bitrate files, the size is easy to predict:
| Bitrate | Size per minute (approx.) | Good for |
|---|---|---|
| 128 kbps | 0.96 MB | Podcasts, lectures, voice notes, audiobooks |
| 192 kbps | 1.44 MB | Music for everyday listening (recommended) |
| 320 kbps | 2.4 MB | Music archives, high-end headphones |
One honest caveat: most MP4 videos already store audio in a compressed format, usually AAC at 96–256 kbps. Converting that to MP3 is a lossy-to-lossy conversion. A higher MP3 bitrate keeps more of what is there, but it cannot improve on the original. For most videos, 192 kbps is the sweet spot.
File size limits and memory
To encode an MP3, the browser first decodes the soundtrack into raw audio samples, which take a lot of memory (about 1.3 GB per hour of stereo sound at 44.1 kHz). That is why the converter states a limit of about 500 MB per file. Computers with plenty of RAM handle long videos comfortably, while phones are happiest with clips under 20–30 minutes. If a long video fails, enter a start and end time and convert it in parts.
Tips
- Speech? Choose 128 kbps and Mono for small files that still sound clear.
- Music? Use 192 kbps Stereo, or 320 kbps if you want maximum fidelity.
- Need a ringtone? Use the trim fields to cut a 20–30 second section.
- Error about codecs? Some downloaded films use Dolby AC-3 audio that browsers cannot decode. Try Chrome or Edge on a computer, or another copy of the video.
- Keep the tab open. Conversion runs in this page, so switching away for a long time on a phone may pause it.
What this tool does not do
It does not download videos from YouTube, TikTok or any other website. It converts files you already have. Please respect copyright, and only extract audio from videos you made or are allowed to use. The output is always 44.1 kHz MP3, the standard rate for music players, and it does not copy metadata tags such as title or artist.
Frequently asked questions
Is this MP4 to MP3 converter free and safe?
Yes. It is free, has no sign-up and does not upload your video. Decoding and MP3 encoding both happen inside your browser, so the file never leaves your device.
Which bitrate should I choose?
192 kbps is a good default for music and sounds very close to the source for most listeners. 128 kbps is fine for speech, podcasts and lectures and makes smaller files. 320 kbps is the highest MP3 bitrate and suits music when space is not a concern.
Will 320 kbps make the audio better than the original?
No. Most MP4 videos already contain compressed audio (usually AAC). Converting to MP3 cannot add back detail that was never there, so 320 kbps only preserves what exists. Bitrates above the source rarely make an audible difference.
Why do I get an “audio could not be decoded” error?
Either the video has no sound track, or its audio uses a codec your browser cannot decode, for example AC-3 or E-AC-3 surround audio found in some downloads and MKV files. Try another browser, such as Chrome or Edge, or a different copy of the video.
Is there a file size limit?
The practical limit is about 500 MB. Your browser has to hold the whole decoded soundtrack in memory, which is roughly 1.3 GB per hour of stereo audio, so very long videos can fail on phones. Use the trim option to convert part of a long video.
Can I convert YouTube videos with this?
This tool converts video files you already have on your device. It does not download from YouTube or other sites. Only convert videos you own or have the rights to use.
Does it work on iPhone?
It works in current Safari, Chrome and Firefox on iPhone, iPad and Android, though phones have less memory than computers. Short and medium-length videos work best.
Why does the converter load a script from jsDelivr?
The MP3 encoder (lamejs, an open-source JavaScript port of the LAME encoder) is downloaded from the jsDelivr CDN only when you press Convert. The exact version is locked with a security hash. Your video is never sent anywhere, only the encoder code comes in.
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By Abdullah Al-Janoubi · WorldScope Tools · Updated October 2026
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