Opus vs AAC

Opus is a free, open lossy codec (IETF standard) that outperforms AAC at low bitrates and also supports lossless compression. Opus wins on quality per bit and openness; AAC wins on real-world device support, especially Apple.

audio format comparison

Opus.opus

Opus is a free, open lossy codec (IETF standard) that outperforms AAC at low bitrates and also supports lossless compression.

Pros

Best-in-class quality at low bitrates (16–64 kbps)
Open standard with no licensing fees
One codec for speech and music, lossy or lossless

Cons

Less hardware support than AAC or MP3
Not playable on some older devices and car stereos
Streaming support is broad but still not universal

AAC.aac

AAC is a widely licensed lossy codec - the default for Apple devices and many streaming services.

Pros

Widespread hardware support (Apple, PlayStation, many car stereos)
Mature ecosystem of encoders and players
HE-AAC variants are efficient for low-bitrate streaming

Cons

Inferior to Opus at low bitrates
Licensing fees apply to some implementations
Not an open standard

Which should you use?

Opus: Choose Opus for web audio, VoIP, or streaming where quality per kilobyte matters.

AAC: Choose AAC when the target is Apple devices or hardware with guaranteed AAC support.

Convert between Opus and AAC

Convert Opus to AAC →Convert AAC to Opus →

Free, runs in your browser - files are never uploaded.

Quick Answer

Opus and AAC are both audio formats with different trade-offs. Opus wins on quality per bit and openness; AAC wins on real-world device support, especially Apple. Choose Opus for web audio, VoIP, or streaming where quality per kilobyte matters. Choose AAC when the target is Apple devices or hardware with guaranteed AAC support.

Key Facts

Opus: Opus is a free, open lossy codec (IETF standard) that outperforms AAC at low bitrates and also supports lossless compression.
AAC: AAC is a widely licensed lossy codec - the default for Apple devices and many streaming services.
Opus strengths: Best-in-class quality at low bitrates (16–64 kbps); Open standard with no licensing fees; One codec for speech and music, lossy or lossless.
AAC strengths: Widespread hardware support (Apple, PlayStation, many car stereos); Mature ecosystem of encoders and players; HE-AAC variants are efficient for low-bitrate streaming.
Opus trade-offs: Less hardware support than AAC or MP3; Not playable on some older devices and car stereos; Streaming support is broad but still not universal.
AAC trade-offs: Inferior to Opus at low bitrates; Licensing fees apply to some implementations; Not an open standard.
Converting between Opus and AAC is lossy in both directions; each re-encode discards a little more data.
Opus wins on quality per bit and openness; AAC wins on real-world device support, especially Apple.

Frequently Asked Questions

Which is better, Opus or AAC?

Opus wins on quality per bit and openness; AAC wins on real-world device support, especially Apple. Choose Opus for web audio, VoIP, or streaming where quality per kilobyte matters. Choose AAC when the target is Apple devices or hardware with guaranteed AAC support.

Is Opus lossless or lossy?

Opus is lossy, so some data is permanently removed to shrink the file. AAC is lossy, so some data is permanently removed to shrink the file.

Can I convert Opus to AAC without quality loss?

Converting between Opus and AAC is lossy in both directions; each re-encode discards a little more data. You can convert either direction with the free tools linked on this page.

What happens to my file when I convert Opus to AAC?

Converting between Opus and AAC is lossy in both directions; each re-encode discards a little more data. Your original file is never modified - the converter downloads a new file.