Does converting MP3 to FLAC improve the quality?

No. FLAC is lossless, so it keeps exactly what it is given, but an MP3 has already lost part of the sound and converting cannot restore it. The FLAC sounds the same as the MP3 and is larger. Convert to FLAC when a system asks for FLAC, and start from a WAV or CD rip when you can.

How much smaller is FLAC than WAV?

It depends on the audio. On our test file, a 1 min 23 s voice recording, the FLAC at level 5 was 59% of the WAV's size. Each converted file on this page shows its own size next to what a WAV of the same audio would weigh.

Which compression level should I pick?

Level 5, the reference encoder's default, suits almost every file. Every level from 0 to 8 is lossless and decodes to the same audio; higher levels make the file a little smaller and take longer, lower levels are faster.

Which files does it take?

MP3, WAV, M4A, AAC, FLAC, AIFF, OGG, Opus, WebM and MP4 files, up to 10 at a time and 100 MB and 30 minutes each. Each file is decoded in your browser's memory, which is why there is a limit; split a longer file with the Audio Trimmer first.

Are my files uploaded?

No. The files are processed in your browser and are not uploaded: the page decodes each one and writes the FLAC on your device. It records ordinary analytics events, such as the level you chose and how many files you converted, not the files or their names.

MP3 to FLAC Converter

Convert MP3, WAV, M4A and other audio files to FLAC, up to 10 at a time, and download them one by one or as a ZIP. Choose the compression level, the bit depth and the sample rate. It works as a WAV to FLAC converter too, and everything runs in your browser; the files are not uploaded.

Drop MP3, WAV or other audio files here or click to browse

MP3, WAV, M4A, AAC, FLAC, AIFF, OGG, OPUS, WEBM or MP4. Up to 10 files, 100 MB and 30 minutes each.

The files are processed in your browser and are not uploaded.

How to convert MP3 to FLAC

Three steps, in your browser.

1
Add your files
Drop up to 10 MP3, WAV, M4A, AAC, AIFF, OGG or other audio files, each up to 100 MB and 30 minutes. The page reads each file's length and sample rate first.
2
Pick the FLAC settings
Level 5 is the usual choice. Bit depth Auto keeps a 24-bit WAV at 24 bits and writes everything else at 16 bits. Keep the sample rate unless your archive or player asks for 44.1 or 48 kHz.
3
Convert and download
Press Convert. Each file is encoded in turn and gets its own download, with its size next to what a WAV of the same audio would weigh. With two or more files, download them all as one ZIP.

Going the other way? FLAC to MP3 makes a small file for any player. For uncompressed audio, use MP3 to WAV.

What the FLAC converter does

Lossless FLAC
FLAC stores exactly the samples it is given, in a smaller file than WAV. Decode the FLAC again and you get the same audio, bit for bit; each file carries a checksum of its audio so players can check it.
Up to 10 files at once
Add a folder's worth of recordings, set the options once and convert the whole list. Every file gets its own download, or take them all in one ZIP.
Compression level 0 to 8
The same scale as the reference flac encoder, with 5 as its default. Every level is lossless; a higher level only spends more time to save a little more space.
Bit depth and sample rate
16 or 24 bits, and the file's own sample rate or 44.1 or 48 kHz. Mono stays mono and stereo stays stereo.

Does converting MP3 to FLAC improve quality?

No. An MP3 throws away part of the sound when it is made, and nothing can bring that part back. Converting the MP3 to FLAC keeps exactly what the MP3 still has, no more and no less, in a lossless file that is much larger than the MP3.

That is still useful when an archive, an editor or a player asks for FLAC: the file then moves through that system without being compressed again. For the best FLAC, start from the original WAV, AIFF or CD rip instead of an MP3.

From a WAV, the FLAC is a true lossless copy: same samples, smaller file. Pick 24 bits (or Auto) for a 24-bit WAV so nothing is rounded off.

How much smaller FLAC is than WAV

Measured with this page's encoder on a 1 min 23 s voice recording (mono, 24 kHz, 16-bit):

File	Size	Share of the WAV
WAV, 16-bit	3.8 MB	100%
FLAC, level 0	2.3 MB	60%
FLAC, level 5	2.3 MB	59%
FLAC, level 8	2.2 MB	59%

How much FLAC saves depends on the audio: quiet passages and simple sound shrink more, dense music less. The compression level changes the size only a little.

When FLAC is the right format

An archive or a DAW that wants FLAC
Some archives, editors and sample libraries accept FLAC but not MP3. Converting once lets the file go in and stay as it is.
Lossless masters from WAV
Keep the mix or the interview master as FLAC instead of WAV: the same audio, in our test 59% of the size, with a checksum of the audio inside.
A player or car stereo that prefers FLAC
Many hi-fi players, phones and car stereos play FLAC. If yours handles FLAC better than WAV, one format for the whole library is simpler.
Which level to pick
Level 5 for almost everything. Level 8 if space matters more than time, level 0 to 2 for a slow computer or a long list.

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