Are my OPUS files uploaded anywhere?

No. This conversion runs entirely inside your browser, so the file never leaves your device. You can confirm it yourself: open the network tab of your browser's developer tools and convert something. You will see the page load, plus the analytics and advertising the site is paid for with — and nothing carrying your file.

Is converting OPUS to M4A free?

Yes. There is no account, no watermark and no limit on how many files you convert — it runs on your own machine, so it costs us nothing to let you. Files up to 100 MB are handled in the browser.

Does converting OPUS to M4A lose quality?

M4A is a compressed format, so some data is discarded. At the default setting the difference is not visible; you can raise the quality setting if you need to be certain. Both formats are compressed, so this is a second round of compression on audio that has already lost detail. Pick the highest quality band if the result is going to be edited or converted again.

Do I need to install anything to open M4A files?

No installation is needed for the conversion itself — it runs in the browser you already have. Opening the M4A afterwards needs whatever software normally handles MPEG-4 Audio on your device.

OPUStoM4A

Convert OPUS to M4A

Up to 100 files at once. Mixed formats are fine.

You can convert OPUS to M4A free and without an account: drop the file above and the M4A is ready to download in a second or two. The conversion happens inside your own browser, so the file is never uploaded — it works on Windows, Mac, Linux, iPhone and Android, and keeps working with the network switched off.

What OPUS and M4A are for

The best-sounding format at low bitrates. What voice messages and calls use.

AAC audio in an MP4 container. What iTunes and voice memos produce.

How to convert OPUS to M4A

Drop your OPUS file onto this page, or click to pick one.
Choose M4A as the target. The conversion runs inside your browser — the file is never uploaded.
Download the finished M4A file.

OPUS vs M4A: what changes

OPUS compared with M4A
	OPUS	M4A
Full name	Opus Audio	MPEG-4 Audio
File extension	.opus	.m4a
Media type	audio/opus	audio/mp4
Compression	Lossy — file size is bought with quality	Lossy — file size is bought with quality

Quality: Some quality is given up for a smaller file. At the default setting the difference is hard to see.
Where it runs: This conversion runs inside your browser. Your file is never uploaded, and it works with the network disconnected.
What can be lost: Both formats are compressed, so this is a second round of compression on audio that has already lost detail. Pick the highest quality band if the result is going to be edited or converted again.

OPUS to M4A: common questions

Are my OPUS files uploaded anywhere?: No. This conversion runs entirely inside your browser, so the file never leaves your device. You can confirm it yourself: open the network tab of your browser's developer tools and convert something. You will see the page load, plus the analytics and advertising the site is paid for with — and nothing carrying your file.
Is converting OPUS to M4A free?: Yes. There is no account, no watermark and no limit on how many files you convert — it runs on your own machine, so it costs us nothing to let you. Files up to 100 MB are handled in the browser.
Does converting OPUS to M4A lose quality?: M4A is a compressed format, so some data is discarded. At the default setting the difference is not visible; you can raise the quality setting if you need to be certain. Both formats are compressed, so this is a second round of compression on audio that has already lost detail. Pick the highest quality band if the result is going to be edited or converted again.
Do I need to install anything to open M4A files?: No installation is needed for the conversion itself — it runs in the browser you already have. Opening the M4A afterwards needs whatever software normally handles MPEG-4 Audio on your device.