What Is FLAC? The Lossless Audio Format Explained
FLAC (Free Lossless Audio Codec) is an open-source audio format that compresses audio files without losing a single bit of quality. Unlike MP3 which permanently discards data, FLAC reduces file sizes by 30-60% compared to WAV while guaranteeing that the decoded audio is mathematically identical to the original. It has become the standard format for audiophiles, music archivists, and anyone who refuses to compromise on sound quality.
How FLAC Lossless Compression Works
FLAC compression works by finding and encoding patterns in the audio data rather than discarding information. The encoder first applies linear prediction, estimating each audio sample based on previous samples. The difference between the prediction and the actual value (the residual) is then encoded using Rice coding, a variable-length encoding that is highly efficient for the small residual values typical in audio.
The key guarantee is that decompressing a FLAC file produces a bit-for-bit identical copy of the original audio data. This is mathematically verifiable — FLAC files include MD5 checksums of the original audio that decoders can verify. Compression levels range from 0 (fastest, least compression) to 8 (slowest, most compression), but the difference between levels is only in encoding speed and file size — decoded quality is always identical.
Advantages and Limitations of FLAC
- Bit-perfect lossless compression — the decoded audio is mathematically identical to the source
- Reduces file sizes by 30-60% compared to uncompressed WAV
- Open-source and completely royalty-free
- Supports up to 32-bit depth and 655 kHz sample rates for hi-res audio
- Rich metadata support with Vorbis comments, album art, and cue sheets
- Streaming-friendly with seekable frames and embedded seek tables
- Files are 3-5x larger than equivalent MP3 at 320 kbps
- Not supported natively in Safari or iOS without third-party apps
- No lossy mode — you cannot create ultra-small FLAC files for mobile use
FLAC vs MP3 vs WAV: Finding the Right Balance
Each format makes different trade-offs between quality, file size, and compatibility.
| Feature | FLAC | MP3 / WAV |
|---|---|---|
| Quality | Perfect (lossless) | MP3: good (lossy) / WAV: perfect |
| File size (4-min song) | 20-35 MB | MP3: 3-10 MB / WAV: 40-50 MB |
| Compression type | Lossless | MP3: lossy / WAV: none |
| Metadata | Rich (tags, art, cue) | MP3: ID3 tags / WAV: minimal |
| Streaming | Supported with seeking | MP3: universal / WAV: not ideal |
| Mobile support | Android yes, iOS limited | Both: universal |
Best Use Cases for FLAC
- Building a permanent music library where quality preservation is the top priority
- Archiving CD collections in perfect digital copies that can always be converted later
- Hi-res audio playback on audiophile equipment (DACs, headphone amps)
- Music production as a delivery format when clients need lossless quality
- Storing master recordings that may need to be re-encoded to different formats in the future
- Tidal, Qobuz, and other lossless streaming platforms that deliver FLAC content
How to Convert FLAC to MP3 or Other Formats
- 1
Decide why you are converting
Convert to MP3 for device compatibility and smaller files. Convert to WAV for DAW compatibility. Convert to ALAC for Apple lossless ecosystem.
- 2
Upload your FLAC file
Use WeLoveConvert to upload your FLAC file. All processing happens in your browser — your music never leaves your device.
- 3
Choose quality settings
For MP3 output, use 320 kbps for best quality or V0 VBR for optimal quality-to-size ratio. For WAV, no settings needed — the output is an exact copy of the audio data.
- 4
Download your converted file
Save the converted file. If you converted to MP3, metadata tags from the FLAC file are preserved in the output.
Frequently Asked Questions
Is FLAC really lossless?
Yes. FLAC is mathematically lossless — decompressing a FLAC file produces a bit-for-bit identical copy of the original PCM audio. Each FLAC file contains an MD5 checksum that can verify the decoded output matches the original source exactly.
Can you hear the difference between FLAC and MP3?
It depends on the bitrate, equipment, and listener. Most people cannot distinguish FLAC from MP3 at 320 kbps on standard headphones. However, on high-quality audio systems, trained listeners can sometimes detect subtle differences, especially in complex orchestral music or high-frequency transients.
Why are FLAC files so much bigger than MP3?
MP3 achieves small file sizes by permanently removing audio information deemed less audible. FLAC preserves every single bit of audio data and relies solely on mathematical patterns to reduce size, resulting in files that are 3-5x larger than MP3 but identical in quality to the original.
Does FLAC work on iPhone?
Starting with iOS 11, iPhones support FLAC playback in the Files app. However, the native Music app does not support FLAC — for that, you need ALAC (Apple Lossless) or a third-party player like VLC.
What is the best FLAC compression level?
Level 5 (the default) offers the best balance between compression ratio and encoding speed. Level 8 produces files only about 2-3% smaller than level 5 but takes significantly longer to encode. All levels produce identical audio quality.
Is FLAC better than WAV?
For storage and distribution, FLAC is superior — it provides identical audio quality in files that are 30-60% smaller, with better metadata support. For editing in DAWs, WAV may be preferred due to wider software compatibility and zero decompression overhead.
Can FLAC files contain album art?
Yes, FLAC supports embedded album art (cover images) in JPEG or PNG format. Most music players and library managers can read and display embedded FLAC artwork.
How do I rip CDs to FLAC?
Use software like Exact Audio Copy (Windows) or XLD (Mac) for bit-perfect CD ripping to FLAC. These tools use secure ripping modes to verify every sector is read correctly, producing FLAC files that are exact digital copies of the CD audio.
FLAC is the gold standard for lossless audio — combining perfect quality preservation with meaningful compression and rich metadata support. Whether you are building an audiophile music library, archiving CDs, or delivering masters to clients, FLAC ensures that not a single bit of audio quality is compromised. When compatibility requires it, tools like WeLoveConvert make converting FLAC to MP3 or other formats quick and private.