Convert between formats
MP3 to MP4, so audio can go where video goes
Most platforms will not accept an audio file. This wraps your MP3 in a plain video track so it uploads like anything else.
Files are processed on your device · nothing is uploaded, stored or logged
How it works
Pick your file. The browser reads it straight from disk. There is no upload progress bar, because there is no upload.
The encoder loads once. A WebAssembly build of FFmpeg, around 30 MB, downloads the first time you use the site and stays cached afterwards.
Your processor does the work. Everything happens in this tab, at roughly half of real time on a modern laptop.
Save the result. The finished file is assembled in memory and handed to your downloads folder.
Why audio needs a video wrapper
YouTube, and most platforms built around video, reject audio files outright. There is no technical reason they could not play an MP3; the upload pipeline simply expects a video stream and refuses anything without one.
The workaround everyone uses is to pair the audio with a still picture. That is what this does, using a plain coloured frame at 1280 by 720.
Because the picture never changes, the video track costs almost nothing. A one-hour MP4 made this way is barely larger than the MP3 that went into it.
If you want artwork instead of a colour
A plain background is the right choice when the upload is a placeholder — a podcast episode, a demo, a track you want a link for. If the video is going to be seen rather than only heard, adding real artwork matters, and that means an editor where you can position and time it properly.
Common questions
Will YouTube accept the result?
Yes. It is an ordinary H.264 MP4 and uploads like any other video.
Can I use my own image?
Not in this tool. It uses a plain colour, which keeps the whole thing to one file and one step.
Does the audio quality change?
It is re-encoded to AAC at 192 kbps, which is transparent for almost all material.
How large will the file be?
Close to the size of the audio. A static picture compresses to almost nothing.