How do I convert MP3 to Opus?

Add your MP3 file to the upload area above, then press Convert. The Opus 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 Opus reduce quality?

Opus 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

MP3 to Opus Converter

Turn MP3 files into Opus in a couple of clicks. The universal lossy audio format. The best low-bitrate codec available — voice and music. 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

MP3 files (.mp3) · up to 300 MB each

or paste files from your clipboard

Ready when you are

Drop a MP3 file above and FileTools360 will turn it into Opus — right here on your device, without uploading anything.

⌘K to search converters

How to use it

1
Add your MP3 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.

MP3 and Opus explained

MP3 is the lossy audio format that made digital music portable. Its patents expired in 2017, which is part of why it remains ubiquitous — anyone can implement it freely.

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.

Where MP3 files come from: Music libraries, podcasts and voice recordings.
Where Opus is used: Voice and video calls, modern podcast pipelines and WebRTC.

MP3 vs Opus

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

MP3 compared with Opus
Property	Source	Target
Compression	Lossy	Lossy
Introduced	1993	2012
Browser support	Plays absolutely everywhere.	Modern browsers and apps; older hardware may not.

MP3 is stronger at: Plays on absolutely everything, including old hardware. Small files. No licensing constraints since 2017.
Opus is stronger at: Best-in-class quality at low bitrates. Extremely low latency, which is why calls use it. Royalty-free.

Why convert MP3 to Opus?

People make this switch when they run into the limits of MP3: archiving masters, or editing audio you will re-export repeatedly. Opus is the better fit when voice content, or any situation where bandwidth is tight.

MP3 limitations that prompt the switch: Lossy — discarded detail cannot be recovered. Beaten on quality-per-byte by AAC and Opus. No native support for multichannel audio in practice.
What you give up: Older hardware and car stereos generally cannot play it. Less recognised by users than MP3.

Does converting MP3 to Opus reduce quality?

Both MP3 and Opus are lossy, so this is a re-encode: the file is decoded and compressed again. At the default quality setting the difference is very hard to see, but each successive re-encode compounds. If you will need the file again later, keep the MP3 original rather than converting back and forth.

Converting MP3 to a lossless format like FLAC does not restore quality. It produces a larger file containing exactly the same degraded audio.