WMA to MP3 Converter
Your old Windows audio, playable everywhere. Drop WMA files, get MP3s back — 100% in your browser. No uploads, no accounts, no limits.
WMA sounds fine and plays almost nowhere outside Windows — phones, car stereos, email, and upload forms all expect MP3. This converts WMA Standard v1/v2, Pro, Lossless and Voice in .wma/.asf files on your device, privately, in batches of 20.
Honest limits: WMA is already compressed, so the MP3 is often about the same size — you convert for compatibility, not to save space; tags are not carried over; MP3 is lossy, so 320 kbps keeps the most; DRM-protected files are refused.
Drop your WMA files (.wma / .asf) here
or — multiple recordings welcome, or paste a copied file
Up to 100 MB per file · up to 15 minutes per recording · up to 20 files per batch · nothing ever uploads
Privacy proof — verify it yourself
This page processes your recordings entirely on your device. All JavaScript and the engine are bundled locally. Your file data never leaves the device — the only third-party requests are the site’s own analytics (Google Analytics and a Cloudflare beacon), which load when the page opens and never see your files. Your recordings are personal; they never leave the machine you are sitting at.
Requests during processing: 0 to this site (the converter engine, fetched in two parts on first use) · 0 to anyone else (none — as it should be)
Converter engine: ffmpeg.wasm — loads on first convert
- Press F12 to open developer tools, then open the Network tab.
- Drop a WMA file above and let it convert.
- Watch the Network tab: no requests while it converts. The counter above shows the same split live. (The page’s own analytics load once when the page opens — before you start — and never touch your files.)
- Bonus: turn your internet off after the page loads and the engine has loaded once — conversion still works.
How to convert a WMA file to MP3 without uploading it
- Drop the .wma or .asf files above — up to 20 at once. Each file’s codec variant (WMA Standard v1/v2, Pro, Lossless or Voice), sample rate, channels, length and bitrate are shown straight away, with an estimated MP3 size at your chosen bitrate.
- Pick a bitrate — or a preset. Speech / voice memo (128 kbps) for spoken recordings, Music (192 kbps) for songs, Best quality (320 kbps) when you want to keep the most detail. Or drag the custom slider to any bitrate from 64 to 320 kbps — matching the WMA’s own bitrate is the smartest choice.
- Listen to each MP3 in the built-in preview, then download it — or grab everything as one ZIP. Your originals are untouched and nothing leaves your device.
Why convert a WMA at all?
WMA was the default audio format of Windows Media Player, Windows recordings, and Microsoft’s old music stores — millions of rips, voice recordings and Zune libraries are still WMA. It sounds good for its size, but outside Windows it barely plays: iPhones, Android phones, car stereos, email clients, and most upload forms and transcription tools only accept MP3. Converting trades a little quality for a file that plays practically anywhere. Keep the WMA as your master copy and share the MP3.
WMA Standard, Pro, Lossless and Voice: what the card shows
WMA is a family, not one codec, and the card names the variant each file actually is — read from the WAVEFORMATEX codec tag in the ASF header, not guessed from the extension. WMA Standard v1 and v2 are the everyday codec (Windows Media Player rips, Windows Sound Recorder). WMA Pro is the higher-quality variant with surround sound. WMA Lossless stores the audio bit-perfect, like FLAC — but converting it to MP3 still loses quality, because MP3 itself is lossy; keep the Lossless original if you care about the last detail. WMA Voice is a low-bitrate speech codec from voice recorders. All five decode here, because the converter core lists all five WMA decoders.
What about .asf files?
A .wma file IS an .asf file: WMA audio lives inside Microsoft’s ASF container, and the .wma extension is just a hint that the container holds audio. This tool accepts .asf files too, and reads the ASF header to find the audio stream. A .asf file that holds WMV video gets its audio converted and its video dropped (the -vn flag); a video-only .asf with no audio track is refused with a clear message.
Honest limitations
- MP3 is lossy, always — there is no lossless MP3 mode. 320 kbps preserves the most; 128 kbps is fine for speech but audible on music.
- WMA is already compressed — the MP3 is often about the same size as the WMA, and can be a little bigger if you pick a higher bitrate than the WMA’s own. The page shows the before and after size on every file, so the result is never a surprise.
- Metadata is stripped — titles, artists and album names stored in the WMA’s ASF header are removed from the MP3 (verified in testing). Keep the original if you need the tags.
- WMA Lossless still loses quality — converting a bit-perfect WMA Lossless file to MP3 is a lossy re-encode: the MP3 can never hold everything the Lossless file did. Keep the Lossless original as your master copy.
- 100 MB / 15-minute caps — in-browser encoding runs slower than real time for long files, so a longer recording would outlast a browser tab session. Split very long recordings first.
- First convert loads the engine — the converter (ffmpeg.wasm, ~31 MB) downloads once from this site on your first conversion. After that it is cached and works offline.
- Low sample-rate WMAs cap the bitrate — an 8 kHz or 11,025 Hz recording encodes at most 64 kbps even if you pick 128, and a 22,050 Hz recording at most 160 kbps, because the encoder caps it (measured in testing). The card tells you when this happens.
- Renamed files are refused — an MP3, FLAC, WAV, Ogg or M4A file renamed to .wma is detected from its contents and refused with a clear message pointing at the right converter. A PNG image renamed to .wma is refused too.
- Protected files are refused — WMA files bought from the old MSN Music, PlaysForSure or Zune stores carry Windows Media DRM: the audio is encrypted and the licence servers are gone, so no tool can convert them. This tool detects the DRM marker in the header and refuses the file with a clear message.
- Not all .asf audio is WMA — an ASF file holding audio in an unrecognised codec is refused with a clear message naming its codec tag, as is a video-only ASF with no audio track. Only WMA Standard v1/v2, Pro, Lossless and Voice are supported.
- MP3-only output — this tool makes MP3s. If you need FLAC or WAV, use a desktop converter.
Frequently asked questions
How do I convert a WMA file to MP3 without uploading it?
Use a tool that converts locally in your browser. This converter loads your WMA file into your device’s memory, decodes it with ffmpeg.wasm running on your machine, and encodes it as MP3 — all with JavaScript and WebAssembly running locally. Your file data never leaves the device — the only third-party requests are the site’s own analytics (Google Analytics and a Cloudflare beacon), which load when the page opens and never see your files. You can verify it by watching the Network tab in your browser’s developer tools while it converts — the live counter on this page shows no requests during processing.
What is a WMA file — and what is WMA Standard, Pro, Lossless and Voice?
WMA is Microsoft’s audio codec, and it lives in the ASF container — a .wma file is really an .asf file with an audio stream, which is why this tool accepts .asf files too. There are five variants, and the card shows which one each file is: WMA Standard v1 and v2 (the everyday codec from Windows Media Player rips and Windows recordings), WMA Pro (higher quality, surround sound), WMA Lossless (bit-perfect storage, large files), and WMA Voice (low-bitrate speech). All five decode here — the vendored converter core lists all five WMA decoders — but a WMA Lossless file still loses quality when it becomes an MP3, because MP3 itself is lossy. Protected files from the old MSN Music, PlaysForSure and Zune stores are refused — their audio is encrypted and no tool can convert them.
Will converting WMA to MP3 lose quality?
Yes, a little: WMA is already lossy (except WMA Lossless), so converting to MP3 is lossy-to-lossy and discards a little more detail — there is no lossless MP3 mode. In practice the difference is small when the bitrates match: at 192 kbps music still sounds very good, and at 320 kbps the difference from the WMA is inaudible for almost everyone. The mistake to avoid is re-encoding a low-bitrate WMA at a high MP3 bitrate — a 64 kbps voice recording re-encoded at 320 kbps just gets bigger, not better. Match the MP3 bitrate to the WMA’s own bitrate (shown on each file card) and keep the WMA as the master copy. And remember: a WMA Lossless file converted to MP3 still loses quality — the MP3 is a lossy re-encode of a perfect original.
Why is my MP3 bigger than the WMA file?
Because WMA is already compressed — WMA is a newer, more efficient codec than MP3, so a WMA at a given bitrate is often smaller than an MP3 at the same bitrate. If your WMA was encoded at 64 kbps and you convert it at the default 192 kbps, the MP3 comes out roughly three times bigger while sounding no better, because the detail was already gone. That is expected, not a bug: pick a bitrate close to the WMA’s own bitrate (each card shows it) and the MP3 lands about the same size. You convert for compatibility — MP3 plays on phones, car stereos, email and transcription tools that never learned WMA — not to save space.
Do MP3s keep my WMA file’s tags and metadata?
No — tags and metadata are not carried over. The converter strips all metadata from the MP3 (titles, artists, and album names stored in the WMA’s ASF header), which was verified in testing: a WMA carrying a title, artist and album produced an MP3 with no trace of any of them. That is partly a privacy win, but if you need the tags, keep the original WMA alongside the MP3.
Can I convert a long WMA recording — how long and how big?
Up to 15 minutes and 100 MB per file, and up to 20 files per batch. Conversion runs in the browser via WebAssembly and scales roughly with length: in our test run a 2-second WMA file encoded in under a tenth of a second once the engine had loaded, so a 9-minute recording takes on the order of half a minute on a typical laptop. Longer files take longer — split very long recordings first.
What bitrate should I choose — and what is the custom bitrate slider for?
Speech / voice memo (128 kbps) for spoken recordings, Music (192 kbps) for songs, Best quality (320 kbps) when you want to keep the most detail. The custom slider covers every valid MP3 bitrate from 64 to 320 kbps, so you can match the MP3 bitrate to the WMA’s own bitrate — a 96 kbps voice recording converts best at 96 kbps, not 320. One honest limit: low sample-rate sources cap the bitrate — an 8 kHz or 11,025 Hz recording encodes at most 64 kbps even if you pick 128, and a 22,050 Hz recording at most 160 kbps, because the encoder caps it (measured in testing). The card tells you when this happens.
Why won’t it convert my old MSN Music or Zune purchase?
Because those files are protected with Windows Media DRM: the audio inside is encrypted, and the key lives with a long-dead licence server, so no tool — this one, a desktop converter, or anything else — can decrypt them. This converter detects the DRM marker in the file’s header and refuses the file with a clear message, rather than failing silently halfway through. Unprotected WMA files — your own rips, Windows recordings, and downloads that were never DRM-wrapped — convert normally. If a file you ripped yourself is refused, check it was not copied from a protected store library.
How do I verify my files really never upload?
Open your browser’s developer tools (F12), go to the Network tab, then convert a file. You will see no requests during processing — the live counter on this page shows the same number. The only requests during processing are the converter engine itself (ffmpeg.wasm, about 31 MB), fetched in two parts from this same site on first use. All JavaScript and the WebAssembly engine are vendored locally. The only third-party requests are the site’s own analytics (Google Analytics and a Cloudflare beacon), which load when the page opens — they never see your files.