ALL AUDIO TOOLS18
WMA to MP3
Convert WMA to MP3 Online — Free & Private
Turn old Windows Media Audio files into MP3s that play on anything.
Nothing is enforced, but every WMA goes through FFmpeg, which expands it to a 16-bit WAV around ten times the size of a 128 kbps source before that is decoded to 32-bit float in this tab — so both have to fit in memory.
About WMA to MP3
WMA is Microsoft's audio format, and if you have any it is probably because a Windows machine ripped a CD with the default settings some time between 1999 and 2012. The files still play in Windows Media Player and VLC, and almost nowhere else — no iPhone, no Mac without extra software, no browser, no modern car stereo, and no upload form. This is the one conversion on the site with no native path at all. Every other audio format here can be decoded by the browser itself on at least some platforms; WMA cannot be decoded by any of them, which means this page always loads the FFmpeg engine — a one-time download of roughly 31 megabytes, served from this site rather than a CDN, cached by your browser afterwards. Everything after that download happens in the tab: FFmpeg decodes the WMA, and the MP3 is encoded from the decoded samples. Because both formats are lossy, this is a second generation of compression, so choose 256 or 320 kbps for music you intend to keep and 128 kbps for anything that is mostly speech. One visible consequence of having no browser decoder: the waveform preview cannot draw itself for a WMA file, so the canvas says the preview is unavailable while the conversion runs perfectly well underneath it. The audio is never uploaded.
Questions
Why does this page always download something?
Because no browser can decode WMA. Every other audio format here has a native path on at least some platform; Windows Media Audio has none, so this page always loads an FFmpeg build compiled to WebAssembly — roughly 31 MB, served from this site rather than a CDN, and cached by your browser afterwards. Everything after that download happens in the tab.
Which kinds of WMA file work?
Standard WMA — the wmav1 and wmav2 codecs that Windows Media Player wrote by default — is what this was tested against end to end. The engine also carries decoders for WMA Pro and WMA Lossless, so those are likely to work, but they were not part of the measurement and we would rather say so than imply otherwise.
Will DRM-protected WMA files convert?
No. Files bought from the old Windows Media stores carry DRM, and the audio inside cannot be decoded without a licence that lives on the machine it was bought for. No browser tool can convert those, and this one will fail on them rather than produce a broken file.
Does the conversion lose quality?
Yes. WMA is lossy and MP3 is lossy, so the file is decoded and encoded again — a second generation of compression. Choose 256 or 320 kbps for music you intend to keep, and 128 kbps for anything that is mostly speech, where the difference is hard to hear.
Why is the waveform preview blank?
The waveform is drawn with the browser's own decoder, and no browser has one for WMA. The canvas says the preview is unavailable rather than pretending, and the conversion runs perfectly well underneath it through the FFmpeg engine.
Is my file uploaded to a server?
No. Transmute processes everything locally in your browser using JavaScript and WebAssembly. Your files never leave your device — there is no server, no upload, no cloud processing.