Opus vs MP3: what is the difference?
Opus is the modern format behind WhatsApp voice notes, Discord and YouTube audio. MP3 is the one everything plays. We measured both on the same music and speech.
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- No size limit
- No sign-up
- Free
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Quick answer: Opus is far more efficient than MP3 at low bitrates: one minute of speech was 0.18 MB as 24 kbps Opus against 0.48 MB as 64 kbps MP3, and Opus is built to sound clear at those rates. At the same bitrate the files are the same size (128 kbps: 0.96 MB each). MP3 plays on almost everything; Opus does not play on many car stereos, older players and some editors, so convert Opus to MP3 for those.
Updated
Choose Opus when
- You stream or send voice: it stays clear at very low bitrates.
- The app uses it already: WhatsApp, Telegram, Discord and YouTube all do.
- Storage or data is tight.
Choose MP3 when
- It has to play in a car, an old player or an editing program.
- You upload it somewhere that lists MP3 but not Opus.
- You send it to someone and want it to just work.
Music and speech, measured
| Recording | Opus | MP3 |
|---|---|---|
| 1 min of music | 0.48 MB at 64 kbps · 0.96 MB at 128 kbps | 0.96 MB at 128 kbps · 2.40 MB at 320 kbps |
| 1 min of speech, mono | 0.18 MB at 24 kbps | 0.48 MB at 64 kbps |
One minute of the Sintel trailer soundtrack (stereo, 44.1 kHz), made with standard free software on 20 October 2026. Sintel © Blender Foundation, CC BY 3.0. One minute of a person reading aloud (mono), made with standard free software on 20 October 2026.
How it works
- Drop your audio fileM4A, WAV, FLAC, OGG and more, any length. It stays on your computer.
- Pick the quality"Very good" suits speech and most music; "Best" for music you care about.
- Download the MP3Plays on every phone, computer, car stereo and audio editor.
Where Opus files come from
- WhatsApp and Telegram voice messages are Opus, saved as .opus or .ogg.
- Discord uses Opus for voice.
- YouTube streams much of its audio as Opus, so audio saved from it often is too.
Why Opus sounds good at low bitrates
Opus was designed in 2012 for calls and streaming, and switches between a speech mode and a music mode as the sound changes. At 24–32 kbps speech stays clear, where MP3 at that rate sounds thin and watery. At 128 kbps and above both sound very good.
Converting Opus to MP3
Pick "Speech" for voice notes: the MP3 is a little bigger than the Opus, which is normal, because MP3 needs more bits for the same clarity. For music pick "Very good". Nothing is uploaded; the conversion runs in your browser.
Measured, not promised
From our tests in Chrome on a 2019 Intel MacBook, October 2026. See all results.
Why your audio never leaves your computer
Online converters upload your file to their servers, convert it there and send it back. That is slow for long recordings, so free plans cap the length or the number of files, and your recording sits on someone else's computer.
Here your own computer does the work, inside this tab. Nothing is uploaded, so there is nothing to cap: no length limit, no daily limit and no sign-up.
Questions
Is Opus better than MP3?
At the same bitrate, yes, most clearly below 96 kbps. MP3 wins on compatibility: more devices play it.
Why is my MP3 bigger than the Opus file?
Opus voice notes use very low bitrates. MP3 needs more bits to sound as clear, so the converted file is bigger.
Can iPhones play Opus?
Not reliably in every app, and many car stereos and older players cannot. MP3 plays everywhere.
Can I convert several files at once?
Yes. Choose or drop several files together. They are converted one after another with the same settings, and you can download each one or all of them in one ZIP.
Is it really free?
Yes. Your computer does the work, so a file costs us nothing to convert. No account and no limits.
Is my file uploaded?
No. It is converted inside this browser tab and saved straight back to your computer.
Which browsers work?
Recent Chrome, Edge and Safari on a computer.
Can I use a video file?
Yes. Drop a video and you get its sound.