Opus vs MP3: Is Opus Better Quality Than MP3?
Opus vs MP3: Opus sounds better at the same bitrate and has far lower delay, but MP3 still plays on more devices. Compare quality, size, support and when to use each.
The quick answer
Opus is the better codec: in published listening tests it beat MP3 and AAC at the same bitrate, it handles both speech and music, and its delay is low enough for live calls. MP3 is the more compatible format: almost every phone, car stereo, player and app reads it. Use Opus where you control playback, such as web apps, voice and modern phones, and MP3 when the file has to play anywhere.
- Quality per bit — in a Hydrogenaudio test at about 96 kbps, Opus beat a 136 kbps MP3.
- Delay — Opus defaults to 26.5 ms and can go down to 5 ms; MP3 needs at least 100 ms.
- Support — MP3 plays almost everywhere; Opus needs Android 5.0+ or a recent Apple OS for full support.
- Need a file that plays anywhere? Convert Opus to MP3 in your browser — nothing is uploaded.
Do it in your browser — free, no upload
MP3 has been the default lossy audio format for three decades. Opus is a much newer open codec, built to handle everything from phone-quality speech to high-quality music in one format. On paper Opus wins almost every technical comparison, yet MP3 is still everywhere. This guide compares them on sound quality, file size, delay and device support, and ends with clear advice on which to use.
The short answer
- Sound quality: Opus sounds better at the same bitrate, especially at low and medium bitrates.
- File size: for similar quality, Opus files can be noticeably smaller.
- Delay: Opus is built for live audio; MP3 is not.
- Compatibility: MP3 plays on almost anything. Opus support is now broad, but older hardware and some apps still lack it.
- Rule of thumb: use Opus where you control playback, and MP3 when a file has to work anywhere.
Two codecs from different eras
MP3 (MPEG-1 Audio Layer III) was finalized in 1992. It became the format of the download era and is supported by nearly every device that plays audio. Its patents have expired (in the US in April 2017), so it is free to use. Normal stereo MP3 files run from 32 to 320 kbps.
Opus was standardized by the IETF as RFC 6716 in 2012. It combines two earlier codecs: SILK, developed at Skype for speech, and CELT, developed at Xiph.Org for low-delay music. The encoder can use either one or both, so the same codec handles a phone call at very low bitrates and stereo music at high ones. It runs from 6 to 510 kbps and is open and royalty-free.
Sound quality
The best public evidence comes from listening tests run by the Hydrogenaudio community and cited by the Opus project:
- Around 64 kbps: Opus scored ahead of two HE-AAC encoders and Vorbis.
- Around 96 kbps: Opus scored ahead of two AAC encoders, Vorbis and an MP3 encoded at 136 kbps.
In other words, at mid bitrates Opus beat an MP3 that had roughly 40% more bits to work with. Wikipedia's summary of the tests is that Opus ranked above MP3, AAC and HE-AAC at any given bitrate until all of them reach transparency, the point where listeners cannot tell the file from the original.
That last part matters. At high bitrates, such as 320 kbps MP3, both codecs are usually transparent for most listeners on most equipment. Opus's advantage is largest where bits are scarce: voice, streaming on slow connections, and small files on a phone.
File size
Size depends only on bitrate and length. One minute of audio takes about:
| Bitrate | Size per minute | Typical use |
|---|---|---|
| 32 kbps | 0.24 MB | Opus voice notes and calls |
| 64 kbps | 0.48 MB | Opus spoken word, casual music |
| 96 kbps | 0.72 MB | Opus music |
| 128 kbps | 0.96 MB | MP3 for casual listening; Opus high quality |
| 192 kbps | 1.44 MB | MP3 good quality |
| 320 kbps | 2.4 MB | MP3 highest quality |
Because Opus reaches a given quality at a lower bitrate, an Opus music library can be noticeably smaller than an MP3 one at similar quality. How much smaller depends on the music and your ears, so test with your own files before converting a whole collection.
Delay
This is the difference that decided where Opus is used. Opus's default delay is 26.5 ms with 20 ms frames, and a low-delay mode goes down to 5 ms. MDN lists MP3's delay as at least 100 ms. Over 100 ms is fine for playing a song, but too slow for a conversation. That is why the WebRTC standard requires Opus support, and why voice and video apps use it. Wikipedia lists Discord, WhatsApp, Zoom and Signal among its users.
Device and app support
MP3 plays on practically everything: phones, computers, browsers, car stereos, smart speakers, old MP3 players and podcast apps.
Opus support is broad but newer:
- Browsers: Chrome since version 33, Firefox since 15, Edge since 14. Safari support came in stages; Safari on iOS has full support from iOS 18.4.
- Android: Opus playback since Android 5.0 (in WebM and Matroska), Ogg files since Android 7.0, and the .opus extension since Android 10.
- Apple: iOS 11 and macOS High Sierra played Opus only inside CAF files. iOS 17 added .opus playback in the Files app, and iOS 18.4 and macOS 15.4 added Ogg support in Safari.
- Players: VLC, foobar2000 and most modern players handle it.
- Older hardware: many car stereos, older Bluetooth speakers and portable players do not read Opus at all.
Where each is used
Opus: voice and video calls (WebRTC), Discord, WhatsApp voice messages, YouTube's WebM audio streams, Signal, SoundCloud and many web apps.
MP3: downloads, podcasts, music shared between people, car USB sticks, DJ software and anywhere a file must open on an unknown device.
Bitrates that work
Xiph.Org, the group behind much of Opus, publishes recommended settings for it:
- Voice calls (mono): 10–24 kbps. Around 24 kbps already gives full-band speech.
- Audiobooks and podcasts: 24 kbps for mono, 32 kbps for stereo.
- Music streaming: 64–96 kbps. Xiph says Opus beats MP3, AAC and Vorbis at these rates.
- Music you store: 96–128 kbps. At 128 kbps (VBR), Xiph calls Opus "pretty much transparent."
- Archiving: FLAC rather than any lossy codec.
For MP3, MDN suggests at least 128 kbps for stereo and at least 192 kbps for music downloads, and many people use 256 or 320 kbps for their own library. Compare those numbers and the size difference becomes clear: an Opus file at 96 to 128 kbps plays the role of an MP3 at 192 to 320 kbps.
Which should you choose?
| Situation | Choose |
|---|---|
| Voice or video calls, live audio | Opus |
| A web app or game you control | Opus |
| Saving space on a modern phone | Opus at 96–128 kbps |
| A public podcast feed | MP3 |
| Files for a car stereo or old player | MP3 |
| Sending music to someone | MP3 |
| An archive you will convert again later | Neither: keep FLAC or WAV |
Converting between Opus and MP3
Both are lossy, so converting from one to the other always loses a little more detail. Converting cannot add back what the first encoder removed.
- Opus to MP3: do this when a device or app will not play Opus. Pick 256 or 320 kbps so the second encode adds as little loss as possible. Use our Opus to MP3 converter.
- MP3 to Opus: this saves space, but each lossy step costs quality. If you still have a lossless original, encode Opus from that instead with WAV to Opus or FLAC to Opus.
- For editing: decode to an uncompressed file first with Opus to WAV.
All of these run in your browser with FFmpeg, so your files are never uploaded. Free users get 5 conversions per month. The output is limited to the first 10 seconds as a preview, with a 20MB input file size limit. Upgrade to Pro for unlimited, full-length conversions.
The bottom line
Opus is the better codec: higher quality per bit, low delay, and one format for speech and music. MP3 is the more compatible file. For anything live, web-based or space-limited where you know the player supports it, use Opus. For anything that has to play on any device, MP3 is still the safe choice.