Why convert FLAC to MP3
FLAC keeps music lossless, but its files are three to five times larger than MP3. For a phone, car or portable player, MP3 at 320 kbps keeps nearly all the quality in far less space.
FLAC is FLAC, lossless compressed audio favoured for music collections; MP3 is MP3, the audio format every player, car stereo and phone plays.
What changes
- FLAC is lossless; MP3 removes sounds people can't hear to save space. 320 kbps is the closest to the original, 192 kbps is the usual balance.
- Sample rate and channels are kept (mono stays mono, stereo stays stereo).
On your device
Your files are converted by your browser and never uploaded, so there is no sign-up, no file-size cap beyond your free disk space and no daily limit. You can convert up to five files at once.
How this works
The file is read in slices by Mediabunny in a Web Worker, which finds the audio track; your browser's built-in decoders (WebCodecs) turn it into sound samples, which are then encoded as MP3 by LAME, the open-source MP3 encoder, compiled to WebAssembly and loaded only when needed, at the bitrate you choose. The result is written to the browser's private storage as it is produced, so long recordings don't need to fit in memory, then offered for download. Nothing is uploaded.
Frequently asked
Which bitrate should I choose?
192 kbps sounds like the original for most listening; 320 kbps for music you care about; 128 kbps for speech and the smallest files.
Are my files uploaded?
No. The conversion runs in your browser on this device; nothing is sent to a server.
Is there a size limit?
Only your device's free disk space. Long recordings are written to the browser's private storage as they are converted.
Sources
- RFC 9639 — Free Lossless Audio Codec (FLAC)
- ISO/IEC 11172-3 — MPEG-1 Audio (including Layer III, MP3)
- Mediabunny documentation — Converting media files
- LAME — open-source MP3 encoder
Reviewed Oct 19, 2026 · test vectors fixtures/convert/audio/flac-to-mp3/