MP4 to MP3 Converter
Convert MP4 to MP3 online, for free.
Maximum file size is 1GB
How it works
Three steps to your converted file
No software to install, no account to create. RunConvert runs entirely in the browser and handles the conversion in the cloud.
Upload your file
Drag and drop any file, click to browse, or paste a URL. Supports 300+ input formats across video, audio, image, document, and archive types.
Choose an output format
Pick from hundreds of output formats. Filter by category or search by name - no sign-ups, no paywalls, just instant access to every option.
Convert & download
Click Convert and your file is ready in seconds. Files are processed on secure cloud servers and automatically deleted after a few hours.
What is an MP4 file?
MPEG-4 Part 14 (MP4) is a digital multimedia container format defined by ISO/IEC 14496-14. Based directly on the QuickTime File Format (QTFF), it allows for streaming over the Internet and is the global standard for video compatibility. An MP4 file can store video streams (encoded with H.264/AVC, H.265/HEVC, or MPEG-4 Visual), audio streams (typically AAC or MP3), subtitles, and still images. It utilizes object-oriented structures specifically designed to support initial object descriptors (IOD) and other MPEG features.
How to open an MP4 file
MP4 is the most widely supported video format in existence. It opens natively on virtually all modern operating systems including Windows (via Movies & TV or Windows Media Player), macOS (QuickTime), Android, and iOS. Web browsers (Chrome, Firefox, Safari) also support native MP4 playback via the HTML5 video tag. No external software is generally required, though VLC Media Player is useful for MP4 files containing obscure codecs.
MP4 Technical Info
- Full Name
- MPEG-4 Part 14
- Developed By
- ISO / IEC
- Initial Release
- 2001
- MIME Type
- video/mp4
What is an MP3 file?
MPEG-1 Audio Layer III (MP3) is a lossy audio compression format defined by ISO/IEC 11172-3, developed by the Fraunhofer Institute. It uses perceptual coding based on psychoacoustic models to discard auditory data deemed imperceptible to the human ear, specifically utilizing the Modified Discrete Cosine Transform (MDCT) and Fast Fourier Transform (FFT). The format structures data into frames consisting of a header and data block, becoming the de facto standard for digital audio transfer in the 1990s.
How to open an MP3 file
MP3 playback is universally supported across all major operating systems (Windows, macOS, Linux, Android, iOS) without requiring additional codec installation. Native applications such as Windows Media Player, QuickTime, and Groove Music handle the format by default. Advanced users seeking spectral analysis or tag editing may utilize Audacity or Mp3tag.
MP3 Technical Info
- Full Name
- MPEG-1 Audio Layer III
- Developed By
- Fraunhofer Society
- Initial Release
- 1993
- MIME Type
- audio/mpeg
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Why RunConvert
The fastest way to convert any file
Purpose-built for speed, privacy, and breadth of format support.
Convert MP4 to MP3 in seconds
Every MP4 to MP3 conversion runs in the cloud - no software to install, no quality compromises.
Fast, cloud-powered
No queue, no waiting. Files are processed on high-performance servers and returned in seconds, even for large files.
Secure & private
256-bit SSL encryption in transit. We never share your files and automatically delete all uploads after processing.
Free - no account needed
Convert files without signing up. No usage limits, no credit card, no hidden fees - full access, always free.
Developer API
Convert MP4 to MP3 via API
Automate MP4 to MP3 conversions in three steps: create a job, upload your file, then poll for the result.
# 1. Create job
curl -X POST https://api.runconvert.com/v3/jobs \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"tag": "mp4-to-mp3",
"tasks": {
"upload-file": {
"operation": "import/upload"
},
"convert": {
"operation": "convert",
"input": "upload-file",
"output_format": "mp3"
},
"export-result": {
"operation": "export/url",
"input": "convert"
}
}
}'
# 2. Upload your file (use upload_url from the response)
curl -X PUT "$UPLOAD_URL" --upload-file input.mp4
# 3. Poll for result
curl https://api.runconvert.com/v3/jobs/$JOB_ID?include=tasks \
-H "Authorization: Bearer YOUR_API_KEY"Replace YOUR_API_KEY with your RunConvert API key. Get your free API key at runconvert.com/api.
FAQ
Frequently asked questions
Common questions about converting MP4 to MP3 with RunConvert.
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