Why MP3 specifically
MP3 is the most-searched-for audio format because it's what most consumer audio recorders default to. Phone voice memo apps, podcast download files, recorded conference talks distributed online — all of them are usually MP3. Other formats (WAV, M4A, FLAC, OGG) all transcribe identically through the same pipeline, but "MP3 to text" is the dominant search query so we make sure the workflow is explicit for that format.
How it works
Upload your MP3 file — any bitrate (32kbps phone-quality through 320kbps studio-quality all transcribe equally well for speech content). Speech recognition processes the audio. Output is plain UTF-8 text with paragraph breaks. Free tier handles MP3s up to ~60 minutes per file; Pro handles multi-hour MP3s in one pass.
For other audio formats
WAV, M4A, FLAC, OGG, AAC, WebM, AMR all work the same way through the Audio to Text tool. If your file isn't MP3 specifically, just use that one — same engine, same output, no quality difference.