Convert MP3 to WMA — Free Online Tool
Convert MP3 files to WMA format using the wmav2 codec, producing Windows Media Audio files compatible with Windows Media Player, Xbox, and Microsoft ecosystem devices. Both formats are lossy, so this conversion re-encodes the audio — ideal when WMA is specifically required for a target platform.
to
FFmpeg Command
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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
Since MP3 and WMA use fundamentally different and incompatible audio codecs (libmp3lame vs. wmav2), this conversion cannot simply remux the existing audio stream — it must fully decode the MP3 audio back to raw PCM and then re-encode it using the WMA v2 codec (wmav2). This is a lossy-to-lossy transcode, meaning the audio undergoes two generations of compression artifacts: once when the original MP3 was created, and again when encoding to WMA. The output is wrapped in the ASF (Advanced Systems Format) container, which is the underlying container format Microsoft uses for WMA files. The default bitrate of 128k is applied unless you specify otherwise.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool. In the browser version of this tool, FFmpeg runs locally via WebAssembly (ffmpeg.wasm) — no data leaves your machine. |
-i input.mp3
|
Specifies the input MP3 file. FFmpeg reads and fully decodes the MP3 audio stream using the libmp3lame decoder, producing raw PCM audio that can then be re-encoded into WMA format. |
-c:a wmav2
|
Sets the audio codec for the output to wmav2 (Windows Media Audio v2), the standard and most compatible version of the WMA codec. This tells FFmpeg to re-encode the decoded MP3 audio into WMA format using Microsoft's WMA v2 specification. |
-b:a 128k
|
Sets the audio output bitrate to 128 kilobits per second. This is a standard WMA bitrate that balances file size and audio quality; you can raise this to 192k or 256k for better quality or lower it to 96k or 64k to reduce file size. |
output.wma
|
Specifies the output filename with the .wma extension. FFmpeg uses this extension to automatically select the ASF container format, which is the proprietary Microsoft container that wraps WMA audio streams. |
Common Use Cases
- Preparing audio files for playback on older Windows Media Player-centric devices, such as certain Zune players, Windows CE devices, or legacy Windows Mobile phones that only support WMA natively.
- Submitting audio content to a Windows-based digital signage or retail audio system that is configured to accept only WMA files in its media library.
- Converting a music library to WMA for storage on an Xbox 360 or original Xbox console, which had native WMA support but limited MP3 compatibility depending on firmware version.
- Packaging audio content for a Microsoft SharePoint or early Windows Media Services streaming server that was configured specifically for WMA delivery.
- Satisfying a corporate IT requirement where internal audio memos or training recordings must be delivered in WMA format to comply with a Windows-locked enterprise media policy.
- Repurposing MP3 podcast episodes or audiobook chapters into WMA for distribution through a legacy Windows-based e-learning platform that only ingests WMA files.
Frequently Asked Questions
Yes, there will be some additional quality degradation because this is a lossy-to-lossy transcode. The MP3 audio is first decoded to raw PCM and then re-encoded with the wmav2 codec, which introduces a second round of compression artifacts. At 128k, wmav2 generally performs comparably to MP3 at 128k in terms of perceived quality, so the loss may be subtle — but it is mathematically irreversible. If you have access to the original lossless source (e.g., WAV or FLAC), encoding directly to WMA from that source will always produce better results than converting from MP3.
WMA v1 (wmav1) is an older codec from the early Windows Media Audio era, while WMA v2 (wmav2) is an improved version that offers better audio quality at equivalent bitrates and is supported by virtually all devices and software that handle WMA files. This tool defaults to wmav2 because it is the modern standard for standard-quality WMA encoding and provides broader compatibility than wmav1 without sacrificing anything in return.
Not directly — MP3 files store metadata using ID3 tags, while WMA files use ASF metadata attributes (sometimes called WMA tags or Windows Media metadata). FFmpeg will attempt to map common ID3 fields like title, artist, and album to their WMA equivalents during conversion, so in most cases basic metadata will be preserved. However, some ID3-specific tags (like embedded lyrics or certain custom fields) may not map cleanly and could be dropped or require manual re-entry in a WMA-aware tag editor.
You can change the output audio quality by modifying the -b:a flag in the command. For example, to encode at 192k instead of 128k, use: ffmpeg -i input.mp3 -c:a wmav2 -b:a 192k output.wma. Supported WMA bitrates include 64k, 96k, 128k, 160k, 192k, 256k, and 320k. Keep in mind that since the source is already a compressed MP3, raising the WMA bitrate above the original MP3 bitrate will not recover detail that was already discarded — it will only result in a larger file.
Yes. On Linux or macOS, you can loop over files in a directory with a shell one-liner: for f in *.mp3; do ffmpeg -i "$f" -c:a wmav2 -b:a 128k "${f%.mp3}.wma"; done. On Windows Command Prompt, you can use: for %f in (*.mp3) do ffmpeg -i "%f" -c:a wmav2 -b:a 128k "%~nf.wma". The browser-based tool processes one file at a time, so the FFmpeg command is the recommended approach for bulk conversions.
WMA support has declined significantly outside the Microsoft ecosystem. Modern streaming platforms, mobile devices, and web browsers do not natively support WMA, whereas MP3 plays virtually everywhere. WMA conversion is typically only justified when a specific legacy device, enterprise system, or Windows-based platform explicitly requires it. If you are unsure whether your target platform needs WMA, it is usually better to keep the file as MP3 to avoid unnecessary quality loss from the transcode.
Technical Notes
The ASF (Advanced Systems Format) container that wraps WMA audio is a Microsoft proprietary format, which means playback support outside of Windows software is reliant on third-party implementations. FFmpeg's wmav2 encoder is a clean-room implementation of the WMA v2 codec and produces files that are broadly compatible with Windows Media Player, Windows Media Center, and devices with Microsoft Plays For Sure certification. Unlike MP3, WMA natively supports DRM (Digital Rights Management) at the container level, though FFmpeg does not apply DRM during encoding — the output WMA files from this tool are unprotected. Metadata is stored as ASF content description and extended content description objects rather than ID3 tags, and FFmpeg will perform best-effort tag remapping. Since both formats are fixed-bitrate lossy codecs in this configuration, there is no lossless escape path — any conversion between them is destructive. The file size of the output WMA will be similar to an MP3 at the same bitrate, as both formats aim for roughly the same bytes-per-second ratio.