Are my M4A 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 M4A to OPUS 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 M4A to OPUS lose quality?

OPUS 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 OPUS files?

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

M4AtoOPUS

Convert M4A to OPUS

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

You can convert M4A to OPUS free and without an account: drop the file above and the OPUS 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 M4A and OPUS are for

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

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

How to convert M4A to OPUS

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

M4A vs OPUS: what changes

M4A compared with OPUS
	M4A	OPUS
Full name	MPEG-4 Audio	Opus Audio
File extension	.m4a	.opus
Media type	audio/mp4	audio/opus
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.

M4A to OPUS: common questions

Are my M4A 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 M4A to OPUS 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 M4A to OPUS lose quality?: OPUS 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 OPUS files?: No installation is needed for the conversion itself — it runs in the browser you already have. Opening the OPUS afterwards needs whatever software normally handles Opus Audio on your device.