Convert MP3 to OPUS
OPUS gets more out of every kilobyte than anything else in common use, especially on speech.
Audio only · up to 10 files · 100 MB each — those numbers protect your memory, not our server
Getting the converter ready — this happens once, then your browser keeps it.
The converter could not start.
The engine files are missing from — copy ffmpeg-core.js and ffmpeg-core.wasm there.
Almost always a mismatched build: the worker is an ES module, so the core has to be the esm one too. Copy ffmpeg-core.js and .wasm from @ffmpeg/core/dist/esm/, not dist/umd/.
not in this build of the converter, so it is not offered.
What you lose
A generation, as always. But OPUS is efficient enough that even at half the bitrate the result is usually indistinguishable from the MP3 it came from.
What you do not gain
A much smaller file for the same perceived quality. Speech in particular can drop to a third of the size with no audible difference.
What it does to the size
Approximate, for stereo audio at the settings this tool uses by default. The real figure moves with the material — silence and speech compress far better than a full mix.
When this is the right conversion
Web delivery, podcasts, voice, or anywhere bandwidth costs money. Not for sending to somebody whose software you do not know — support is still patchy.
Other conversions
This tool is free because dbelo is a library of sound effects, and we would rather you found us this way than not at all.
Browse the sound library