MP3 to FLAC Converter
Convert MP3 to lossless FLAC audio, with your choice of sample rate and bit depth.
🔒 Processed locally — nothing is uploadedMP3 audio files
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FLAC gives you a smaller file than WAV with no loss of audio data — a genuine middle ground between MP3's aggressive compression and WAV's raw size. This tool decodes an MP3 with your browser's own audio engine, then runs it through a real FLAC encoder (compiled to WebAssembly) entirely on your device, with your choice of sample rate and bit depth.
What "lossless" actually means here
FLAC compresses audio the same way a .zip file compresses a document: purely mathematically, with every original sample recoverable exactly on decode. That's fundamentally different from MP3, which discards information it judges perceptually unimportant and can never get back. FLAC typically lands at 40–60% of an equivalent WAV file's size — a real, useful saving, just nowhere near MP3's roughly 90% reduction.
Choosing a sample rate and bit depth
An MP3 never holds more detail than its own sample rate (almost always 44,100 or 48,000 Hz) at roughly 16-bit precision, so Keep original at 16-bit is the sensible default — it stores everything the MP3 actually contains without inflating the file for no benefit. Bump the sample rate up only if a specific piece of downstream software requires it; 24-bit is mainly useful when you're chaining this output into further audio processing that benefits from extra headroom, not for playback quality on its own.
When FLAC is actually worth it
- FLAC-only media servers. Some home media servers, network streamers and hi-fi apps only fully index lossless formats, even when the underlying source was originally lossy.
- Consistent library format. Keeping an entire collection in one container simplifies tagging, artwork embedding and playback behavior across different apps and devices.
- Smaller than WAV for the same losslessness. If a workflow requires an uncompressed-equivalent file but storage space matters, FLAC gets there in roughly half the space of WAV.
- Not a fix for a bad-sounding MP3. If the original MP3 was encoded at a low bitrate, converting it to FLAC won't make it sound any better — re-encode from the original lossless source if one still exists.
Frequently asked questions
What is FLAC and how is it different from MP3?
FLAC is a lossless compression format — it shrinks a file by roughly 40–60% versus raw WAV using purely mathematical, reversible compression, so decoding a FLAC file reproduces the exact original samples bit-for-bit. MP3 is lossy: it permanently discards audio detail to shrink the file much further.
Does converting MP3 to FLAC restore the quality MP3 removed?
No. FLAC is lossless from the point of encoding onward, but it can only losslessly store what's already there. Whatever detail the original MP3 compression discarded is gone permanently — this conversion won't add it back.
Why convert MP3 to FLAC at all, then?
Mainly compatibility and library consistency: some media servers, hi-fi streamers and archival systems only index or prefer FLAC, and keeping a music library in one consistent lossless-container format (even from lossy sources) simplifies tagging and playback across devices.
What sample rate and bit depth should I choose?
Keeping the original sample rate at 16-bit is normally the right choice — an MP3 source never had more resolution than its own sample rate and roughly 16-bit precision, so a higher setting just adds file size without adding real detail.
Will the encoded FLAC file be byte-for-byte identical to one made with the reference FLAC command-line encoder?
Not necessarily at the compressed-byte level — this tool uses a WebAssembly build of the FLAC encoder, which can make slightly different internal compression choices than the reference encoder. It decodes back to exactly the same audio samples either way, which is what lossless actually guarantees.
Does this tool upload my audio file anywhere?
No. Decoding and encoding both happen locally in your browser — the file never leaves your device.