Drop a WAV, FLAC, OGG or M4A file. The page decodes it with the Web Audio API and encodes MP3 with LAME. A player appears when the file is ready so you can listen before downloading.
Bitrate
96 kbps is for voice notes. 128 is classic speech/podcast. 192 is the default for music. 256 and 320 spend more bits on cymbals and stereo width; the jump from 256 to 320 is small on laptop speakers.
Sample rate
Auto maps unusual rates (including 96 kHz) onto 44.1 or 48 kHz, which LAME accepts. Force 44.1 kHz for CD-style archives or 48 kHz if the rest of your project is video.
Mono
Mono averages the two channels. Use it for interviews and lecture captures; leave stereo for music.
Up to ten files sit in the list. They encode one by one. Change a setting and press Convert again.