How do I convert Opus to M4A?

Add your Opus file to the upload area above, then press Convert. The M4A file downloads straight to your device. You do not need an account, and there is no watermark.

Are my files uploaded to a server?

No. This conversion runs entirely inside your browser using WebAssembly, so the file never leaves your device — you can even disconnect from the internet after the page loads and it will still work.

Does converting to M4A reduce quality?

M4A uses lossy compression, so some data is discarded. At the default quality the difference is very hard to see or hear; raise the quality setting if you need to be certain, at the cost of a larger file.

How large a file can I convert?

Up to 300 MB per file for this conversion. Because the work happens in your browser, the practical limit is your device's memory — larger files work on a desktop with plenty of RAM and may fail on an older phone.

Can I convert several files at once?

Yes. Add as many as you like and press Convert All. Each file is processed independently, so one failure does not stop the rest, and you can download everything together as a ZIP.

Can I use this on my phone?

Yes. FileTools360 works in mobile browsers on iOS and Android, including choosing files straight from your camera roll. Very large videos may run out of memory on a phone — those are better converted on a laptop.

AudioAdjustable qualityRuns in your browser

Opus to M4A Converter

Turn Opus files into M4A in a couple of clicks. The best low-bitrate codec available — voice and music. MP4 container holding AAC or ALAC audio. The output is re-encoded, so quality depends on the settings you choose.

On your deviceNever uploadedGone when you close the tabHow this works

Drop your files here

Opus files (.opus) · up to 300 MB each

or paste files from your clipboard

Ready when you are

Drop a Opus file above and FileTools360 will turn it into M4A — right here on your device, without uploading anything.

⌘K to search converters

How to use it

1
Add your Opus files
Drag them onto the upload area, choose them from your device, or paste them from your clipboard. You can queue several at once.
2
Adjust the settings if you want to
The defaults suit most people. Open Advanced to control bitrate, sample rate and channels and start and end times.
3
Convert and download
Press Convert. Everything happens on your own device — nothing is uploaded. Download files one by one, or grab them all as a ZIP.

Opus and M4A explained

Opus is the current state of the art for lossy audio, and the codec behind most voice calls you make over the internet. It performs well across an unusually wide range, from 6 kbps speech to transparent music.

M4A is an MP4 container holding only audio — usually AAC, sometimes Apple Lossless. The extension exists mainly so players know not to look for a video track.

Where Opus files come from: Voice and video calls, modern podcast pipelines and WebRTC.
Where M4A is used: iTunes purchases, Apple Music downloads, voice memos and audiobooks.

Opus vs M4A

The two formats solve different problems, which is why converting between them involves trade-offs rather than a straight upgrade.

Opus compared with M4A
Property	Source	Target
Compression	Lossy	Lossy or lossless
Introduced	2012	2001
Browser support	Modern browsers and apps; older hardware may not.	Very good, especially on Apple platforms.

Opus is stronger at: Best-in-class quality at low bitrates. Extremely low latency, which is why calls use it. Royalty-free.
M4A is stronger at: Excellent quality per byte. Proper chapter support, which is why audiobooks use it. Strong metadata and artwork handling.

Why convert Opus to M4A?

People make this switch when they run into the limits of Opus: playback on older or embedded hardware. M4A is the better fit when apple ecosystem, audiobooks, or podcasts with chapters.

Opus limitations that prompt the switch: Older hardware and car stereos generally cannot play it. Less recognised by users than MP3.
What you give up: Less universal than MP3 on older or cheaper hardware. The extension hides what codec is actually inside.

Does converting Opus to M4A reduce quality?

Both formats store the content without discarding data, so this conversion preserves it exactly. The file size may change because the two formats compress differently, but the content itself is unaffected.