Upload a Opus file and get a MP3 back. No signup, no watermark, no limit on how many.
Opus is the best lossy codec in general use: at 64 kbps it beats formats running at twice that, which is why real-time applications standardised on it.
Where you run into it: WhatsApp and Telegram voice notes, Discord, Signal, Zoom, and most browser-based calls.
What it costs you: Everything can play it inside an app and remarkably little can play it as a file — a voice note saved to a desktop is the classic case, and the usual reason to convert one.
MP3 is the format that made portable music work, and thirty years on it is still the one every device, car stereo, DAW and browser will open without being asked twice.
Where you run into it: Downloads, podcast feeds, old music libraries, anything a client sends you and expects you to just play.
What it costs you: It throws audio away to get small, and at 320 kbps almost nobody can hear what went. What matters is that the discarded part never comes back.
There is a trap on this page worth knowing about before you choose a setting. Opus is the most efficient lossy codec in general use — at 24 kbps it carries speech better than MP3 manages at twice that — so the number on your .opus file badly understates what is in it. Decoding it and encoding an MP3 at a matched bitrate therefore throws away a great deal, not because MP3 is bad but because you asked it to do the same job with far less. Opus always decodes at 48 kHz, which is exactly the highest rate MP3 can carry, so nothing is resampled here.
Nearly every .opus is a voice message or a Discord recording, and the reason to make an MP3 of one is that MP3 is the format other software assumes. Transcription services, older DAWs, phone systems, court and clinic record systems, and most web forms take MP3 and have never heard of Opus. Keep the .opus as well: it is a fifth of the size and, for speech, the better file — you are converting for compatibility, not for quality, and it is worth being clear with yourself about which one you are buying.
Yes, entirely, and there is no cap on how many files you convert. No account, no watermark, no trial.
A little, and the bitrate you pick decides whether it is a little or a lot. This is the one conversion on the site where matching the source's number is a clear mistake: a 24 kbps voice note re-encoded as a 24 kbps MP3 comes out obviously worse, because MP3 was never designed to work in that territory. Best, or 128 kbps for speech, keeps what is there. The overshoot feels wasteful and is not — you are paying for the gap between two codecs of very different eras.
Considerably larger, and that is the correct outcome rather than a problem. A one-minute voice note at 24 kbps is around 180 KB; the MP3 that preserves it honestly is closer to 1 MB. Reading that growth as a failure is the mistake this page exists to prevent — if your MP3 comes out roughly the same size as the .opus, you have chosen a bitrate that discards most of what the file was carrying.
Not here. Opus can be read but not written by this converter — ffmpeg decodes it happily, and encoding back to it would mean a format almost nothing plays. If you need the original Opus, keep it rather than recreating it.
The file is uploaded to do the conversion — nothing here runs in your browser — and both your upload and the converted result are deleted the moment the file is sent back. Nothing is stored and nothing is logged beyond the request itself.