Convert MP4 to MP3 online

If you already have an MP4 video saved on your device and just need the audio, this converter extracts the soundtrack and saves it as MP3 without touching the original video. Everything happens in your own browser: we never upload the file to a server.

What's converting an MP4 to MP3 good for?

It's handy when you've got a recorded lecture, an interview, a video podcast or a song saved as MP4 and only want to keep the audio: it weighs far less than the full video and plays on any phone, car stereo or speaker. Unlike downloading YouTube videos and converting them to MP3 straight from a link, this converter starts from an MP4 file you already have — one you recorded yourself, say, or downloaded earlier.

How it works: converted in your browser, not on a server

We use ffmpeg compiled to WebAssembly, the same technology behind many video-editing programs, but running inside your browser tab. When you hit 'Convert', the file is processed locally: the audio is split from the video and encoded as MP3 without the MP4 ever leaving your machine. The result downloads directly, just like any other file.

Steps to convert your MP4 to MP3

• Choose the MP4 file from your device ('Choose file' button).
• Hit 'Convert'. The first time, your browser downloads the conversion engine (a few MB); after that, it's faster.
• Wait for the progress bar to reach 100%.
• Download the resulting MP3 with the 'Download result' button.

About the MP4 and MP3 formats

MP4 is a container that bundles video and audio into a single file; it's the most compatible video format there is. MP3, in turn, is the most universal audio format: any phone, computer, car or speaker plays it without any further conversion. Extracting the audio from your MP4 gives you a standard MP3 encoded with libmp3lame at a high variable bitrate (roughly 190 kbps on average), which keeps the original sound intact without producing an unnecessarily heavy file.

Honest limits worth knowing

Since the conversion happens in your browser, the real limit is your device's memory and processing power, not an artificial cap of ours. With normal-sized videos (up to a few hundred MB) the process takes seconds or a couple of minutes. With very large files (above 2 GB) or very long videos, the conversion can take longer or run out of memory on phones with limited RAM — try a computer if that happens. This converter processes one file at a time, on a single thread, so it's not built for batch-converting dozens of videos or for heavy video re-encoding.

Other related conversions

If your audio file is already in M4A rather than video, use the M4A to MP3 converter. And if what you have is a video in another container and want it in MP4 first, try MKV to MP4. If you don't have the file yet and want to download it from YouTube, use our YouTube video downloader.