MP3 to MP4 Converter
Convert MP3 to MP4 online for free: nothing to install, no watermark, files encrypted in transit and deleted automatically after conversion.
Advanced options
Drag & drop your MP3 file here, or
How to convert MP3 to MP4 in 3 steps
- 1
Upload your MP3 file
Drag and drop or select the MP3 file you want to convert.
- 2
Choose MP4 as output
The output format is pre-selected for you — just confirm and start the conversion.
- 3
Download your file
Once processing finishes, download your converted MP4 file instantly.
MP3 vs MP4: what is the difference?
| MP3 | MP4 | |
|---|---|---|
| Full name | MPEG-1 Audio Layer III | MPEG-4 Part 14 |
| Type | Compressed audio | Video container |
| Compression | Lossy | Depends on the codec |
| Developed by | Fraunhofer IIS / MPEG | MPEG (ISO/IEC) |
| File extension | .mp3 | .mp4 |
What is MP3?
MP3 is the classic compressed audio format. It removes sounds the ear barely notices to shrink files to roughly a tenth of CD size, and it plays on every phone, car stereo and music app, which is why it remains the default for music and podcasts.
What is MP4?
MP4 is the most widely used video container. It usually carries H.264 or H.265 video with AAC audio, and it plays on practically every phone, browser, smart TV and editing program, which makes it the safest choice for sharing and uploading.
Tips for converting MP3 to MP4
- Converting a compressed file such as MP3 to a lossless format does not restore detail already removed; it only makes the file larger.
- For music, a lossless source (WAV or FLAC) gives the best result when you convert to MP4.
- Check that your player, car stereo or editing app supports MP4 before converting a whole library.
- Keep the original MP3 file as a backup until you are happy with the converted audio.
Frequently asked questions
- How do I convert MP3 to MP4 online?
- Upload your MP3 file above, select MP4 as the output format, and click Convert. ConvertFastHub processes the file in the cloud and gives you a download link — no software installation required.
- Is it free to convert MP3 to MP4?
- Yes. Free accounts get 10 conversions every 24 hours with files up to 50MB. For unlimited conversions, larger files up to 1.5GB, and priority processing, upgrade to ConvertFastHub Pro.
- Is my file safe when I convert it?
- Files travel over an encrypted connection, are scanned automatically for malware (files up to 200 MB), are processed in an isolated worker and are deleted automatically: after 1 hour without an account, 24 hours with a free account, or 7 days with Pro.
- Can I convert MP3 to MP4 on my phone?
- Yes. The converter runs in the browser and the work happens on our servers, so it works the same on Android, iPhone, tablets and computers — there is no app to install.
- Do I need an account?
- No. You can convert without signing up; results are then kept for 1 hour. A free account keeps them for 24 hours and shows your conversion history.