MP3 to Opus Converter
Opus is the codec behind WebRTC calls and most voice messages, and it keeps music and speech clear at bitrates where MP3 struggles. Convert MP3s here to cut their size for the web, a bot or a long spoken-word archive.
Audio Converter
or drop MP3, WAV, M4A … files here ·
Max 95 MB per file· Up to 20 files· Deleted after 30 minutes
Files are processed on our servers and deleted after 30 minutes.
Constant bitrate (CBR) gives a predictable size and works on every player. Variable bitrate (VBR) spends bits where the music needs them and is usually smaller at the same quality.
Keep the source rate unless a device asks for one. 44.1 kHz is CD standard, 48 kHz is video standard, 8 kHz is used by phone systems and AMR.
Mono halves the size of lossless files and is fine for voice recordings.
16-bit is CD quality. 24-bit keeps headroom for editing and mastering; converting a 16-bit source up does not add detail.
Optional. Seconds (e.g. 75) or minutes:seconds (1:15). Leave empty to start at the beginning.
Optional. Same format as the start time. Leave empty to keep everything up to the end.
How to use this tool
- 1
Add MP3 files
Select up to 20 MP3s, each up to 95 MB: songs, podcast episodes, lectures or sound effects.
- 2
Choose a bitrate
Bitrate is 96 kbps in Variable (VBR) mode, Opus's natural setting. Use 64 kbps for speech, 128 kbps if the MP3 is 256 kbps or more.
- 3
Convert to Opus
Press Convert to Opus and download the .opus files, ready for an
<audio>tag, a bot or your archive.
To convert MP3 to Opus, upload the files and press Convert to Opus. At the default 96 kbps VBR, a typical 192 kbps MP3 shrinks to about half its size, with music and speech that most listeners cannot tell apart from the source.
Why convert MP3 to Opus at all
Opus was designed for real-time speech and music over the internet, merging Skype's SILK speech codec with Xiph.Org's CELT music codec. Because the encoder switches between the two techniques as the signal changes, it handles a podcast, a phone call and a pop song equally well, and it stays clean at bitrates where MP3 starts to sound watery.
That makes it the practical choice when bandwidth or storage costs money: background music for a web app, sound clips sent by a chat bot, a few hundred hours of lectures kept on a phone. Discord, WhatsApp and every WebRTC video call already use Opus internally. If you are sending the files to people rather than code, MP3 or MP3 to AAC remains the safer format for old players.
MP3 to Opus: storage per hour of audio
- MP3 at 320 kbps144 MB
- MP3 at 192 kbps86 MB
- Opus at 128 kbps58 MB
- Opus at 96 kbps43 MB
- Opus at 64 kbps29 MB
From an IETF draft to the web's default voice codec
2012
RFC 6716
The IETF publishes Opus as a standard, with bitrates from 6 to 510 kbps.
2016
RFC 7845
Ogg encapsulation is specified, defining the .opus files you download here.
2016
RFC 7874
WebRTC makes Opus mandatory for every compliant browser and app.
2017
MP3 patents end
MP3 becomes royalty-free too, so the choice is now about size and support.
| MP3 | Opus | Ogg Vorbis | |
|---|---|---|---|
| First released | 1993 | 2012 | 2002 |
| Bitrate range | 8–320 kbps | 6–510 kbps | about 45–500 kbps |
| Royalty-free today | yes | yes | yes |
| Plays in Chrome, Firefox and Edge | yes | yes | yes |
| Required by WebRTC | no | yes | no |
| Car stereos and older players | Nearly all | Rare | Some |
MP3 and Opus specifications
MP3
MP3 audio
MP3 (MPEG-1 Audio Layer III) is a lossy audio format developed largely at the Fraunhofer Institute and standardised by MPEG in 1993. It removes sounds the ear is unlikely to notice, shrinking music to about a tenth of CD size at 128–320 kbps. All patents have expired, and every phone, car stereo, browser and media player supports it. Quality loss is audible at low bitrates and accumulates with re-encoding.
- Compression
- Lossy
- Transparency
- –
- Animation
- –
- Introduced
- 1993 · Fraunhofer IIS / MPEG
OPUS
Opus audio
Opus is an open, royalty-free lossy audio codec standardised by the IETF in 2012. It adapts from low-bitrate speech to full-band music and has very low latency, so it is used by WhatsApp voice messages, Discord, Zoom, WebRTC and YouTube. At the same bitrate it generally beats MP3 and AAC. Many older players, car stereos and editors cannot open .opus files.
- Compression
- Lossy
- Transparency
- –
- Animation
- –
- Introduced
- 2012 · IETF (Xiph.Org, Skype, Mozilla)
MP3 is the format most audio already exists in, and Opus is what web apps, voice bots and space-conscious archives prefer, because it holds the same music or speech at roughly half the bitrate; converting trades universal playback for much smaller files.
MP3 to Opus: questions
Will Safari and iPhones play the .opus files?
Support has arrived later on Apple platforms than elsewhere and still depends on the system version and the container. Chrome, Firefox and Edge play Ogg Opus everywhere. For a web page that must work on every device, keep an MP3 or AAC fallback in a second <source> element.
What Opus bitrate should I use for an audiobook or lecture?
Speech is where Opus is strongest. 32 to 48 kbps in mono is enough for clear voices, though the lowest bitrate option here is 64 kbps, which leaves plenty of headroom for spoken word. Set Channels to Mono for a single speaker to give all of those bits to one channel.
Why is my Opus file almost as big as the MP3?
You probably kept a bitrate close to the MP3's own. Opus only saves space when you let it run lower: a 192 kbps MP3 converted at 96 kbps comes out about half the size. There is no benefit in encoding Opus above the source MP3's bitrate.
Does an MP3 to Opus conversion add a second layer of loss?
Yes, as with any lossy-to-lossy step, although at 96 kbps or more it is very hard to hear. Opus also resamples the audio to 48 kHz, its internal rate, which is harmless. If you have the WAV or FLAC original, encode Opus from that instead.
Is Opus the same as OGG?
Ogg is the container and Opus is one codec that can live in it, alongside the older Vorbis. Files named .opus are Ogg files holding Opus audio. Game engines and mod tools that ask for .ogg usually mean Vorbis, which MP3 to OGG produces.
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