Convert AAC to OPUS
Free online AAC to OPUS converter that runs in your browser. Your files stay on your device.
How to convert AAC to OPUS
- Add your AAC file. Drag it onto the box above, click to browse, or paste it from the clipboard. Multiple files are fine.
- Check the target. OPUS is preselected. Pick High, Medium or Small quality depending on whether you need a master copy or a small file.
- Download. The conversion engine loads once (32 MB) and then your file is processed locally. The OPUS file downloads automatically when it is done.
Why convert AAC to OPUS?
AAC files are not supported everywhere. Converting to OPUS produces the smallest files at a given quality, ideal for voice and messaging.
AAC vs OPUS
| AAC | OPUS | |
|---|---|---|
| Full name | Advanced Audio Coding | Opus |
| Type | Audio | Audio |
| MIME type | audio/aac | audio/opus |
| About | AAC is the successor to MP3, used by YouTube, Apple and most streaming services. Raw .aac streams are less portable than M4A. | OPUS is the most efficient lossy codec available, used by WhatsApp, Discord and WebRTC. Excellent for speech and music at low bitrates. |
What makes this converter different
- Nothing is uploaded. Other converters send your file to a server, queue it, and keep a copy for hours. Here the work happens in your browser with WebAssembly, so private videos, voice memos and documents never leave your computer.
- No limits, no sign-up, no watermark. There is no server to pay for, so there is no reason to cap file size or count.
- Real ffmpeg quality. Video and audio use the same ffmpeg encoders professionals use (x264, LAME, libvpx, FLAC), not a stripped-down web codec.
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Frequently asked questions
Is it safe to convert AAC to OPUS here?
Yes. The conversion runs entirely inside your browser using WebAssembly. Your file is never uploaded to a server, so nothing can leak, be stored or be seen by anyone. You can even disconnect from the internet after the page loads.
How long does AAC to OPUS conversion take?
Audio converts at roughly 20–50× real time, so a 5-minute song takes about 10 seconds after the one-time engine download.
Is there a file size limit?
There is no server-side limit because there is no server. The practical limit is your device memory: browsers can handle files up to about 2 GB. Very large videos work better on a desktop than a phone.
Will the quality drop?
OPUS is a lossy format, so a small amount of detail is discarded. At the default Medium setting the difference is invisible or inaudible for almost all content. Choose High for master copies or Small for messaging and web use.
Can I convert several AAC files at once?
Yes. Drop or select as many files as you like; they are converted one after another and each gets its own download button.