Converting MP3 to MP4 gives you the same content in a different container. It runs in your browser: nothing is uploaded, there is no queue and no size limit.
What changes when you convert MP3 to MP4
- Both MP3 and MP4 are lossy. Every re-encode discards a little more detail, so convert from the original when you can and keep the quality setting at 85 or above.
- Video needs pictures, so we render a waveform animation from the sound. The result posts anywhere that only accepts video.
When to convert, and when not to
Convert to MP4 for sharing video with anyone, anywhere. H.264 video and AAC audio. Plays on absolutely everything.
Keep MP3 for music and podcasts for any device. The universal lossy audio format.
How to convert MP3 to MP4
- Drop your MP3 file on the converter above, or click to choose. Several at once is fine.
- Check the options if you need them: video quality.
- Click Convert, then Download. Nothing was sent anywhere, your browser did the work.
Questions
Is my MP3 file uploaded?
No. The conversion runs in your browser with WebAssembly. There is no upload endpoint on this site. You can open your browser's Network tab, or go offline after the page loads, and it still works.
Is there a file size limit?
No fixed one. The limit is your device's memory: a large audio file on a phone is slower than on a laptop, but nothing is rejected for being big.
Is it free?
Yes, without an account, without a daily cap and without a watermark. Your device does the computing, so there is no server bill to pass on.
Will the quality drop?
MP4 is lossy, so a little detail is traded for a smaller file. At quality 85 the difference is invisible on photos. For graphics with sharp edges, prefer a lossless format such as PNG.
Can I convert several files at once?
Yes. Drop them all; each is converted in turn and you can download them one by one or as a single ZIP.
Which engine does the conversion?
Media engine (FFmpeg, multithreaded WebAssembly), compiled to WebAssembly and running in your browser, on all your CPU cores when the browser allows it. First use downloads about 31 MB, cached afterwards.