Skip to content
All audio conversions

AAC to OPUS converter

Convert AAC to OPUS in your browser. No upload and no account: the file never leaves your device, so the only size limit is your device’s memory.

I want OPUS
Advanced 4
sec

Leave both at 0 for the whole file.

sec
Channels

Bytes of your files sent anywhere: 0 B

Related conversions

Other ways to convert AAC

Convert other formats to OPUS

Read more about the AAC format and the OPUS format, or see every audio tool and all audio conversions.

Should you convert AAC to OPUS?

Fine when a player or app needs OPUS. Converting between two lossy formats compresses the sound a second time, so match or exceed the original bitrate to keep the loss inaudible.

AAC is a bare AAC audio stream without the M4A wrapper; OPUS is the most efficient audio codec in common use, especially for speech. Use Opus for speech and streaming where small size matters more than compatibility.

AAC and OPUS compared
Property AAC OPUS
Compression Lossy Lossy
Typical quality 96–256 kbps 24–128 kbps
Support Opens almost everywhere Has patchy support
Best for Recordings captured from streams and broadcast Voice notes, calls and streaming at low bitrates
Introduced 1997 2012

How to convert AAC to OPUS

  1. 01

    Add your AAC

    Drop your AAC file onto the box, or click to choose it. It is read from your disk and stays there.

  2. 02

    Check the settings

    The output is already set to OPUS. Change the bitrate if you want to; the defaults suit most files.

  3. 03

    Save the OPUS

    Press convert and save the OPUS. Several files come back together as a ZIP.

What changes when AAC becomes OPUS

Two rounds of compression

Each lossy encode throws away a little more. A AAC at 128 kbps converted to OPUS at 192 kbps sounds like the original; converted at 96 kbps it can turn swirly and dull.

Opus runs at 48 kHz

Opus always works at 48 kHz internally, so other sample rates are converted. It sounds excellent at low bitrates, especially for voice.

Expect a smaller file

OPUS usually stores the same content in less space than AAC. AAC: About 1 MB a minute at 128 kbps. OPUS: A minute of voice note is often under 200 KB.

This page is put together from our notes on each format, choosing only what is true of AAC and OPUS, so every pairing states the same facts the same way. How these pages are made.

Why it doesn’t upload

Recordings are often private: interviews, voice notes, unreleased music. Your browser can decode and encode audio itself, so there is no reason to send it anywhere.

How to check for yourself

Worth knowing

  • About the AAC. Raw AAC has no index, so players often show the wrong duration or can’t seek; saving it as M4A fixes both.
  • About the OPUS. WhatsApp voice notes exported from a phone are Opus files, sometimes named .ogg, which many players and transcription services refuse.
  • MP3, WAV, M4A, OGG, Opus and FLAC are converted by your browser directly. WMA, AMR, APE, AC3 and the other specialist formats use the FFmpeg engine, a one-time 31 MB download.

Questions

Does converting AAC to OPUS lose quality?

OPUS is lossy, so a little is discarded, but at the default bitrate the difference is inaudible for nearly everyone.

Will an OPUS play in my car or on my phone?

OPUS has patchy support: browsers, Android and chat apps; many media players, editors and forms can’t open .opus files.

Other tools