In this guide
FLAC is a lossless audio codec: a supported PCM source can be encoded and decoded without changing its samples. It can save space compared with uncompressed PCM, but playback compatibility and a recording’s earlier history still matter.
Choosing a lossless format? Compare FLAC and Apple Lossless.
Choosing a format? Compare FLAC and MP3 for quality, storage and playback.
FLAC stands for Free Lossless Audio Codec. It compresses supported digital audio so a decoder can reconstruct the encoded PCM samples without the losses introduced by a lossy codec such as MP3. A native FLAC file commonly uses the .flac extension and can contain metadata such as tags and artwork.
Lossless describes the relationship between the audio fed into the encoder and the decoded samples. It does not prove that the recording was made at a particular quality, that an earlier source was lossless or that two different masters sound the same. The FLAC specification, RFC 9639, defines the format and its PCM encoding.
How does lossless compression work?
A FLAC encoder represents supported PCM sample data more compactly by exploiting predictable relationships between nearby samples. The decoder reconstructs the sample values. Compression efficiency depends on the signal and encoder settings, so two recordings of equal duration and sample rate need not produce equal-size FLAC files.
A lossless encode is not the same as a file that has never been changed. If an MP3 is decoded and saved as FLAC, the FLAC can preserve those decoded samples, but it cannot recover information already discarded when the MP3 was made. Start from the best available original and keep it when creating delivery copies.
FLAC, WAV and MP3 at a glance
| Format | Typical use | What to check |
|---|---|---|
| FLAC | Losslessly compressed compatible PCM for storage or playback. | Player and editor support, source history, sample rate, bit depth and channels. |
| WAV with PCM | Often uncompressed audio used for editing or exchange. | WAV is a container; confirm the actual encoding and destination requirements. |
| MP3 | Lossy compressed listening or delivery copy. | Encoding discards information and may introduce delay or padding; retain the original. |
A FLAC and a PCM WAV decoded to the same samples do not differ in those samples merely because one is compressed. File size, metadata and software support can still differ. For a detailed comparison, see FLAC vs WAV; for lossy formats, see lossy vs lossless audio.
How to open a FLAC file
- Start with the original file. Confirm it is a native .flac file and keep a copy. A filename alone does not prove a file is valid.
- Choose a compatible player or editor. Check the app’s supported formats and version, then open the file and play several sections. Support can depend on the operating system and the file’s audio properties.
- Check the details you need. For an editing handoff, confirm sample rate, bit depth and channel count in a suitable inspector or editor. Verify tags and artwork separately if they matter.
- If it will not play, troubleshoot before converting. Test the original in another compatible app and check whether the file is complete. Apple’s media playback troubleshooting guide recommends checking app and device support and software updates.
When should you convert FLAC to WAV or MP3?
Convert to PCM WAV when your destination accepts the appropriate WAV encoding but not FLAC. A lossless FLAC-to-PCM conversion can preserve the decoded samples when the output supports the source properties and no resampling, bit-depth reduction or other processing is applied. Metadata may not transfer in the same way.
Choose MP3 when a smaller, widely supported lossy delivery copy suits the task. It is a new lossy encode. Compare the actual file and keep the FLAC so you can make another copy without re-encoding from the MP3. The FLAC-to-MP3 guide covers bitrate and export checks.
Convert a compatible short FLAC to WAV
- Open the FLAC-to-WAV converter and choose a native mono or stereo FLAC with 8-, 16- or 24-bit audio at 8–192 kHz.
- The input and output must each fit 50 MiB, and the recording must be no longer than five minutes. A compressed FLAC can expand beyond the WAV size limit.
- The browser decodes the file locally and compares reconstructed PCM with the embedded FLAC audio checksum. If the checksum is missing or does not match, the tool does not offer a WAV.
- Download the verified WAV and test it in the destination editor. The checksum checks decoded audio against the file’s embedded checksum; it does not prove the recording’s provenance or preserve every tag or image.
These are the converter’s limits, not limits of every FLAC file or decoder. Saturalabs’ separate isolation workflow lists MP3, WAV, MP4 and MOV as upload formats rather than FLAC. A compatible PCM WAV can be a preparation step, subject to that workflow’s own file limits; conversion does not start isolation or separate sources.
Common questions
Is FLAC always high-resolution audio?
No. FLAC can store supported PCM at different sample rates and bit depths. Inspect the file rather than inferring its properties from the extension.
Is a FLAC file always smaller than a WAV file?
Often it is smaller than an uncompressed PCM WAV containing the same audio, but compression depends on the source and file overhead. Compare the actual files.
Can FLAC restore a low-quality MP3?
No. It can losslessly store the decoded MP3 output, but it cannot restore information lost in the earlier encoding.
Is FLAC the same as Apple Lossless?
Both are lossless audio codecs, but they are different formats. Check the codec and the receiving application’s support rather than assuming one file type will work everywhere.