Convert MP3 to OPUS
Drop in an MP3 and get a much smaller .opus file that keeps nearly all of the quality. Everything runs locally in your browser, so the file never leaves your device.
Why convert MP3 to OPUS?
Opus does more with fewer bits than MP3, which is why modern software keeps standardizing on it. Discord streams voice in Opus, WhatsApp voice notes are Opus files, and modern browsers play it natively. That efficiency matters when you are packing sound effects into a web game, shrinking years of lecture or podcast recordings, or building a soundboard or bot that needs small files. If your MP3 collection is eating storage, Opus copies take a real bite out of it. The trade is compatibility: older car stereos and legacy MP3 players usually cannot read .opus files, so keep that in mind before converting everything.
Quality and file size
Going from MP3 to Opus is a lossy to lossy transcode, so a small generation loss is unavoidable. Opus cannot recover anything the original MP3 encoder threw away; it can only re-compress what is left. To keep that loss inaudible, encode at a generous bitrate (256 kbps is a safe choice for music) and resist the urge to convert the same file repeatedly, since each round-trip compounds the loss. Because Opus is much more efficient than MP3, the output will usually still be smaller than the source at comparable quality. If you ever get access to a lossless original, convert from that instead.
MP3 to OPUS: common questions
Will my MP3 sound worse as Opus?
Slightly, in theory, since both formats are lossy and transcoding compounds the loss. At 256 kbps the difference is inaudible for nearly everyone. What you cannot do is improve quality: no conversion can add back what MP3 already removed.
Is my audio uploaded to a server?
No. The converter is FFmpeg compiled to WebAssembly, running inside your browser tab. Your MP3 never leaves your device, and we never see it, store it, or train on it.
Why is the Opus file smaller than my MP3?
Opus is a newer codec that packs the same perceived quality into fewer bits than MP3, especially for speech. At a matching quality level it simply needs less space.
Will .opus files play everywhere my MP3s did?
Not quite. Browsers, Discord, WhatsApp, VLC, and most modern software handle Opus well, but older car stereos, some DAWs, and legacy portable players do not. Keep the MP3 if you rely on aging hardware.
Who makes this?
We're the small team behind Xport Studio, a private, fully offline app for AI vocals, stems, and mastering. These free tools are side experiments we wanted to share. No upsell, but if you're curious about the bigger thing, take a look.