Convert MP3 to Opus online

Your MP3 file is converted to Opus right here in your browser, using FFmpeg compiled to WebAssembly. Nothing is uploaded to us, the audio never leaves your device. Quality is preserved and the download is ready in seconds.

What is an MP3 file?

MP3 (MPEG-1 Audio Layer III) is the format that made digital music portable in the late 1990s, and it remains the most universally supported audio format ever made. It compresses audio by discarding detail the ear is least likely to miss, at bitrates typically between 128 and 320 kbps.

Almost everything plays MP3: every phone, car stereo, browser, WhatsApp attachment and email client. It is the safe default when you don't know what device the other person has.

Why Opus?

Opus is the newest major audio codec (standardised in 2012) and the best-in-class at speech and low bitrates. Which is exactly why WhatsApp voice notes are Opus files. It was designed for real-time internet audio and it is what Discord, WhatsApp and most VoIP apps use.

Convert to Opus for the smallest possible file that still sounds clear, voice at 32 kbps Opus sounds better than at double the bitrate in MP3. Ideal for sharing long voice recordings over limited data. MP3 is showing its age: newer lossy formats like AAC and Opus sound better at the same file size, and every re-encode of an MP3 loses a little more detail.

Frequently asked questions

Will converting MP3 to Opus lose quality?

A small, one-time generational loss is unavoidable. Both MP3 and Opus are lossy, so re-encoding discards a little more detail. The converter uses high-quality settings to keep it inaudible for speech, but if you still have the original uncompressed source, converting from that instead is always better.

Is it free?

Yes, completely, with no account and no watermark. The conversion runs on your own device, so it costs us nothing to let you use it. The only limit is file size: up to 50 MB, which is what a browser can hold in memory comfortably.

Do I need to install anything, or upload my file?

Neither. It runs entirely in your browser using FFmpeg compiled to WebAssembly. Your audio is never sent to us, which is also why it works on a slow connection, only the page downloads, not your file.

Need a transcript of the audio?

Autrans also transcribes audio in Nigerian English, Pidgin, Yoruba, Hausa, Igbo, French, and Spanish.