MP4 to MP3 Converter
Extract audio from MP4, WebM, or MOV. Choose bitrate up to 320 kbps — no uploads.
Best for extracting a podcast, lecture, or music track from a video file.
Drop files or a folder here
or click to browse · paste from clipboard
Accepts .MP4, .WEBM, .MOV · Up to 1,000 files
How it works
Drop your files
Click to browse, drag and drop, or paste from clipboard. Process up to 1,000 files per batch. For larger files, convert batches of up to 50 only.
Choose settings
Adjust bitrate and Sample rate. If you’re not sure what to choose, the default setting is enough for most applications.
Click Convert
Everything runs in your browser via WebAssembly. MP4 to MP3 Converter happens locally — no server involved.
Download
Download files individually or grab all at once as a ZIP.
What is an MP4?
MP4 is the default video format that most websites accept today. When you record videos on your Android phone, it saves as an MP4 file. It’s one of the most efficient at encoding data and doesn’t consume as much space compared to legacy formats like AVI or WMV. It’s the default choice of most content creators because of its universal compatibility across different platforms (YouTube, Facebook, etc.).
An MP4 file at its core is a container that can hold the following:
- Video tracks
- Audio
- Subtitles and metadata
MP4 files support H.264 or newer HEVC (H.265) codec and AAC for audio. A nearly hour-long MP4 video with audio recording will be less than 800 MB. If you’re storing videos as backup on the cloud or hard drive, the memory savings do add up.
What is an MP3?
MP3 is a file format that only stores audio tracks. There’s no video or photos, just sound. This format has been the standard for podcasts, music, audiobooks, and voice recordings for over two decades.
Because it stores only voice, it has a smaller file size than MP4 and works with nearly every modern device, including smartphones, CD players, old iPods, Windows, Mac, and Linux. Its small footprint makes it easy to send via email, messaging apps, and websites.
A 30-minute recording in MP3 will take only 20 to 30 MB, about ten times smaller than an MP4 file.
What to expect
- Expect the file size to drop between 85 and 95% depending on the settings. For example, a 767 MB MP4 file shrinks to 104.5 MB (or an 88% drop), and that’s with the highest bitrate setting. Using the default setting, the file size shrinks to 49.8 MB. Remember that the higher the bitrate, the larger the file size.
- Audio quality doesn’t change, even with the default setting.
- The length won’t change, so a 30-minute video will stay at 30 minutes.
- Video data like subtitles, markers, and thumbnails are deleted since MP3 doesn’t support these.
- Users can convert up to 1,000 files per batch. However, for larger files, keep the batches down to around 50 or less, especially if you’re using an older computer with less memory.
Quality settings, explained simply
Bitrate means how much data the MP3 file stores per second. The higher the bitrate, the better the sound (in theory), but at the expense of a larger file.
| Setting | Bitrate | Best for |
|---|---|---|
| Standard (default) | 128 kbps | Voice memos, lectures, podcasts where you only need to understand the words. Small files. |
| Good | 192 kbps | Almost everything. Music, interviews, mixed content. Sounds the same as the source to most people. |
| High | 256 kbps | Music you’ll listen to on good headphones or a stereo. |
| Maximum | 320 kbps | Max quality MP3. For archiving. Barely different from Good in blind tests. |
If you’re not sure what option to choose, leave it on the default setting. It will sound fine most of the time.
How MP4-to-MP3 conversion actually works (the simple version)
Imagine an MP4 file being a box that has two containers inside: one for video and another for audio. Converting an MP4 file to an MP3 format consists of two steps:
- The first step is opening the audio container and throwing away the video container. The first step is instant. You’re just copying what’s already there.
- The next step is re-encoding the audio container in MP3 format since MP4 uses an AAC format, which is different.
This tool utilizes ffmpeg.wasm, a WebAssembly version of ffmpeg. This is the same tool that professionals use for video and audio encoding. The difference for ConvertYard is that this tool runs in your browser instead of on a server.
Why does “in your browser” matter?
Most free MP4 to MP3 converters upload your video to their server, convert it there, and send you a link to download the converted file. This means.
- Your video file is stored on someone’s computer
- If it’s a large video, you’ll need to wait for the video to upload first before the conversion process starts.
- Large files (e.g., lectures or long recordings) may hit a file size cap
- Private recordings that may contain confidential information are uploaded to an unknown server.
ConvertYard runs the conversion inside your browser so nothing is uploaded. Your MP4 files stay on your computer. It’s faster, more private, and will handle large files if your computer has enough memory.
When you should NOT use this tool
There are instances where you shouldn’t use this tool and other formats are better.
- You’ll need to edit the audio first. If you use a WAV format (which is lossless), you may want to stick to it so you don’t lose audio quality while editing.
- You need the smallest possible audio format for a podcast recording. If that’s the case, try using ACC/M4A at 64 kpbs, which is smaller than an MP3 file at the same quality.
- If you need to store the whole video and not just the audio, try using the Compress Video tool instead.
- Your MP4 file has no audio. This tool will return an error that says the video doesn’t have an audio track.
Frequently asked questions
In most cases, there isn’t any noticeable difference in audio quality, especially if they listen on their smartphones or stock car stereos. MP3 files are a lossy format, so some audio degradation occurs when you convert. One workaround is to use a higher bitrate. 192 to 256 will work for most use cases, but if you want to edit the audio later, use the highest setting (320 kbps).
MP3 files are much smaller than MP4 files because they're lossy and don't include a video track. Based on my tests, the difference is between 85 and 98%, depending on the setting you choose. For example, a 54-minute video that’s 767 MB can shrink to around 52.3 MB, more than a 95% drop.
Converting an MP4 file to MP3 requires decoding a video container, extracting the audio, and then re-encoding it as an MP3 using a media processing engine (or ffmpeg.wasm), so it takes longer per file. This processing engine is about 25 MB and takes a moment to load, but once it does, subsequent conversions will be faster.
Yes. The MP4 to MP3 tool also supports WebM and MOV files, along with MP4, two of the most common video formats.
This tool will not convert an MP4 file that doesn’t have an audio track. You’ll see an error message if you try to convert such. Long videos close to 1 hour will take 3 to 8 minutes (this is approximate), but the actual time will depend on how fast your computer is; more specifically, how much memory it has. If your MP4 file is corrupt, this tool will either return an error message or a corrupt file.
Nope. The MP4-to-MP3 conversion happens in your browser and is not uploaded to a server. So nothing leaves your device. So the ConvertYard server loads the code on your browser and the conversion happens inside the browser and not on a server.