Convert WMA to MP3 — Free Online Tool
Convert WMA files to MP3 by transcoding Windows Media Audio (wmav2/wmav1) into the universally compatible MPEG Audio Layer III format using the LAME encoder. This is ideal for breaking free from Microsoft's proprietary codec and making your audio playable on virtually any device, app, or platform.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your WMA file here
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Settings
Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
WMA files store audio encoded with Microsoft's proprietary wmav2 (or older wmav1) codec inside an Advanced Systems Format (ASF) container. Since MP3 uses a completely different codec (MPEG Audio Layer III, encoded here via libmp3lame), a full audio transcode is required — the WMA audio is decoded from wmav2 back to raw PCM audio, then re-encoded from scratch into MP3. There is no shortcut remux possible here because the codecs are incompatible. This re-encoding process introduces a second generation of lossy compression, so the output quality is bounded by the quality of the original WMA source. The output is wrapped in a standard MP3 container with ID3 tag support.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program, the open-source multimedia processing engine that powers this conversion both in the browser (via FFmpeg.wasm) and on the desktop command line. |
-i input.wma
|
Specifies the input file — a WMA audio file using Microsoft's ASF container, which FFmpeg will demux and decode from wmav2 (or wmav1) format into raw PCM audio for re-encoding. |
-c:a libmp3lame
|
Selects the LAME MP3 encoder as the audio codec, which transcodes the decoded WMA audio into MPEG Audio Layer III (MP3) format — the most universally compatible lossy audio codec across devices and platforms. |
-b:a 128k
|
Sets the MP3 output bitrate to 128 kilobits per second, a standard quality level suitable for general listening. Since the WMA source is also lossy, increasing this beyond the original WMA bitrate will not recover lost detail but will increase file size. |
output.mp3
|
Defines the output filename and container. The .mp3 extension tells FFmpeg to write a standard MP3 file with an ID3 tag header, compatible with virtually all audio players, mobile devices, and streaming platforms. |
Common Use Cases
- Playing purchased or ripped WMA music files on iPhones, iPods, or Apple devices, which have never natively supported the WMA codec
- Uploading audio to platforms like SoundCloud, Spotify for Artists, or podcast hosts that accept MP3 but reject WMA files
- Importing WMA tracks into audio editors like Audacity or GarageBand that have limited or no WMA support without additional plugins
- Archiving an old Windows Media Player music library in a format that will remain playable without Microsoft software or codecs decades from now
- Sharing audio files with colleagues or clients who use non-Windows systems where WMA playback requires installing extra codecs
- Stripping DRM-free WMA files from old CD rips or digital downloads and converting them to MP3 for use in DJ software or media servers like Plex
Frequently Asked Questions
Because both WMA and MP3 are lossy formats, converting between them means decoding the WMA (which already discarded some audio data during its original encoding) and then re-encoding that result as MP3, introducing a second round of lossy compression. At the default 128k bitrate, quality loss is usually subtle but can be audible on headphones, particularly with complex audio like orchestral music. To minimize degradation, match or exceed the original WMA bitrate — if your source WMA was encoded at 192k, output at 192k MP3 or higher.
Yes — WMA files protected with Microsoft's DRM (Digital Rights Management) cannot be decoded or converted by FFmpeg, including this tool. FFmpeg will fail or produce a silent/corrupt output file when it encounters a DRM-locked WMA. This tool only works on DRM-free WMA files, such as those ripped from CDs using Windows Media Player with DRM disabled, or legally obtained DRM-free downloads.
FFmpeg will attempt to map WMA's ASF metadata tags to MP3's ID3 tag format during conversion, and common fields like title, artist, album, and track number typically carry over correctly. However, WMA supports some Microsoft-specific metadata fields that have no direct ID3 equivalent, so those may be dropped. If preserving every metadata field is critical, verify the output tags with a tool like Mp3tag after conversion.
Replace the value after -b:a in the command. For example, to output at 320k (the highest quality MP3 bitrate), use: ffmpeg -i input.wma -c:a libmp3lame -b:a 320k output.mp3. Alternatively, to save space with a smaller file, use 96k or 64k. Keep in mind that choosing a bitrate higher than the original WMA bitrate does not recover lost quality — it only increases file size without audio benefit.
Yes, on the command line you can loop over all WMA files in a directory. On Linux or macOS, use: for f in *.wma; do ffmpeg -i "$f" -c:a libmp3lame -b:a 128k "${f%.wma}.mp3"; done. On Windows Command Prompt, use: for %f in (*.wma) do ffmpeg -i "%f" -c:a libmp3lame -b:a 128k "%~nf.mp3". This browser-based tool processes one file at a time, so the command-line approach is recommended for bulk conversions.
WMA's wmav2 codec is generally more efficient than MP3 at the same bitrate, meaning a WMA file at 128k often sounds comparable to an MP3 at a higher bitrate. When converting WMA to MP3 at equal bitrates (both 128k), the resulting MP3 file will be a similar size but may sound slightly less clean, because MP3 is a less efficient codec. If the original WMA was encoded at a lower bitrate (e.g., 64k) and you output at 128k MP3, your output file will be noticeably larger without any real quality gain.
Technical Notes
WMA uses Microsoft's Advanced Systems Format (ASF) container with the wmav2 audio codec (or the older wmav1 found in files from the early 2000s). Neither codec is natively supported in most non-Microsoft ecosystems, making WMA a format with poor long-term portability. The conversion to MP3 via libmp3lame is a full decode-and-reencode transcode — there is no stream copy possible. The LAME encoder used here produces standard MPEG-1 Layer III audio at the specified bitrate (defaulting to 128 kbps). One important limitation is WMA's DRM system: any WMA file protected with Microsoft's PlayReady or older Windows Media DRM will be unreadable by FFmpeg and cannot be converted. Additionally, WMA supports gapless playback metadata that has no equivalent in standard MP3 (MP3 gapless playback requires the unofficial LAME Gapless header), so gapless album listening may be affected in the output. Metadata mapping from ASF tags to ID3v2 is handled automatically by FFmpeg but may not be perfectly lossless for all tag types.