Unlike MP3 or AAC which permanently discard inaudible frequencies, FLAC uses a reversible prediction algorithm. It models the correlation between audio samples, stores only the prediction residuals (errors), and applies entropy coding to those residuals. The result: a file 40–60% smaller than WAV that decodes identically to the original PCM — every sample, every time. The process is mathematically guaranteed to be lossless by the codec specification.
Free Online FLAC Converter
Convert Audio to Lossless FLAC
Preserve every detail of your music with FLAC — the audiophile's format of choice. Convert WAV, MP3, AAC, AIFF, OGG and more to lossless FLAC with adjustable compression levels.
True lossless audio quality
40–60% smaller than WAV
Supports 24-bit hi-res audio
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Up to 100 MB free • Outputs: FLAC
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Simple & Fast
How to Use FLAC Converter
Convert your files in three simple steps — no software, no signup.
01
Upload Audio or Video
Drop any audio file (WAV, MP3, AAC, AIFF, OGG, M4A) or video file and we'll extract the audio stream.
02
Set Compression Level
FLAC compression levels 0–8 affect encode/decode speed and file size, but never audio quality — all levels are perfectly lossless.
03
Download FLAC File
Get your high-resolution lossless FLAC file ready for archiving, audiophile playback, or further editing.
Features
Why Use FLAC Converter?
True Lossless Compression
FLAC encodes audio without discarding any information. Your audio is bit-for-bit identical to the source after decoding.
Smaller Than WAV
FLAC files are typically 40–60% smaller than uncompressed WAV, saving significant storage space without any quality trade-off.
Hi-Res Audio Support
FLAC supports up to 32-bit / 192 kHz — well beyond what human hearing can detect — making it future-proof for high-resolution music.
Rich Metadata
FLAC uses the Vorbis comment standard for metadata, supporting detailed tags including lyrics, replay gain, and custom fields.
Audiophile Standard
Used by Bandcamp, Qobuz, and high-resolution music stores worldwide — FLAC is the preferred archival and distribution format for serious listeners.
Archive Your Music
Convert your CD rips and studio masters to FLAC once and keep them forever — a lossless archive you can always convert from later.
Compatibility
Supported Formats
All the formats you need, all in one place.
| Format | Description | Extension | Best Used For |
|---|---|---|---|
| WAV → FLAC | Compress lossless WAV to smaller FLAC | .wav |
Archiving studio recordings, saving disk space |
| MP3 → FLAC | Wrap MP3 in FLAC container (no quality gain) | .mp3 |
Format unification of existing libraries |
| AAC → FLAC | Convert Apple AAC to open FLAC format | .aac |
Moving away from Apple ecosystem |
| AIFF → FLAC | Apple lossless to open lossless standard | .aiff |
Cross-platform archive conversion |
| OGG → FLAC | Convert Vorbis to lossless FLAC | .ogg |
Upgrading game audio archives |
| M4A → FLAC | Convert Apple M4A/ALAC to FLAC | .m4a |
iTunes library migration to open formats |
| MP4 → FLAC | Extract lossless audio from video | .mp4 |
Archiving concert video audio tracks |
FAQ
Frequently Asked Questions
Yes. FLAC (Free Lossless Audio Codec) uses a prediction algorithm to compress audio without discarding any data. When decoded, the output is bit-for-bit identical to the original PCM audio.
No — all FLAC compression levels (0 through 8) produce identical audio quality. Higher levels take longer to encode but produce slightly smaller files. Level 5 is the default and a good balance.
Both are lossless codecs that compress audio without quality loss. FLAC is an open standard supported on virtually every platform. ALAC (Apple Lossless) is Apple's equivalent, used in .m4a files on Apple devices. Use our M4A Converter to convert between them.
No. Converting a lossy file to FLAC does not restore lost audio data. The FLAC file will contain the same audio information as the MP3 source, just stored in a lossless container. Always archive from the highest-quality source available.
FLAC is supported on Android, Windows, Linux, most hi-fi streamers (Sonos, Roon, Audirvana), Plex, VLC, and most modern DAPs (digital audio players). Apple devices support FLAC natively since iOS 11 and macOS Sierra.
A typical 3-minute stereo WAV at 44.1 kHz / 16-bit is about 30 MB. The equivalent FLAC file is typically 15–20 MB — roughly a 40–50% reduction with zero quality loss.
Real-World Uses
Who Uses FLAC Converter?
From everyday users to professionals — see how people rely on this tool every day.
Music Archivist
Archive Your CD Rips Losslessly
Convert WAV CD rips to FLAC and cut archive size in half while ensuring the audio is bit-perfect for future use.
Audiophile
Build a Hi-Res Music Library
Store 24-bit / 96 kHz high-resolution music in FLAC — the format supported by Qobuz, Bandcamp, and audiophile streaming services.
Apple User
Migrate iTunes Library to Open Format
Convert M4A/ALAC files from your iTunes library to FLAC to gain cross-platform compatibility without any quality loss.
NAS / Plex User
Serve Lossless Audio on Plex or Roon
FLAC is natively supported by Plex, Roon, Jellyfin, and Audirvana — convert your WAV masters to FLAC for efficient storage on a home media server.
Bandcamp Artist
Upload Lossless for Fan Downloads
Bandcamp lets fans download in FLAC. Convert your WAV master to FLAC before uploading to offer the best lossless download option.
Film Producer
Archive Concert and Film Audio
Extract and archive the audio from concert MP4 files as FLAC — preserving the full dynamic range for documentary and archival use.
Why TransmuteBox?
TransmuteBox vs. Alternatives
See how we compare to desktop software and other online converters.
| Feature |
Our Tool TransmuteBox |
Desktop App | Other Online |
|---|---|---|---|
| True lossless quality | |||
| 24-bit hi-res support | |||
| Smaller than WAV | |||
| Rich metadata / tags | |||
| No software install | |||
| Open standard | |||
| Free to use |
Under the Hood
Technical Specifications
Built on industry-standard open-source tools for maximum quality and reliability.
Limits & Restrictions
- Max file size: 500 MB
- Output compression level: 5 (default)
- Multi-channel up to 8 channels
FFmpeg
FLAC
Lossless
Hi-Res
Vorbis Tags
Open Source
Conversion Engine
FFmpeg 6.x · libFLAC encoder · compression level 0–8
Output Quality
Lossless up to 32-bit / 192 kHz; bit-perfect decode guaranteed
Average Speed
Typical encode: 5–20 seconds for a 100 MB WAV source
Data Security
HTTPS transfer · isolated temp dir · auto-purged in 2 h
Codec
FLAC (libFLAC)
Size vs WAV
40–60% smaller
Max Res
32-bit / 192 kHz
Auto-Delete
2 hours
Complete Guide
FLAC: The Audiophile Archive Format
FLAC (Free Lossless Audio Codec) occupies a unique position in digital audio: it combines the absolute quality of uncompressed PCM with the storage efficiency of compression. For anyone serious about preserving music in its original form, FLAC is the definitive choice for digital audio archives.
How FLAC Compression Works
FLAC Compression Levels: Which Should You Choose?
FLAC offers compression levels 0 through 8. Contrary to intuition, the level never affects audio quality — all levels produce bit-perfect output. The only difference is encode/decode speed and resulting file size. Level 0 is fastest with the largest output; level 8 is slowest with the smallest. Level 5 is the widely used default: it compresses well and completes quickly enough for large libraries. For encoding thousands of files, level 3 or 4 is a practical compromise.
FLAC vs ALAC: Choosing Between Open and Apple
FLAC and Apple Lossless (ALAC) are both lossless codecs with equivalent audio quality. The key differences are ecosystem and openness. FLAC is an open standard maintained by the Xiph.Org Foundation, supported on Linux, Android, Windows, most hi-fi hardware, and (since iOS 11) Apple devices. ALAC is Apple's proprietary format stored in M4A containers — well supported in the Apple ecosystem but less universal. If you are not locked into Apple hardware, FLAC is the better long-term choice.
Metadata with FLAC: Vorbis Comment Tags
FLAC uses the Vorbis Comment standard for metadata, which is flexible and extensible. Beyond the standard tags (TITLE, ARTIST, ALBUM, DATE, TRACKNUMBER, GENRE), you can store LYRICS, REPLAYGAIN values, ISRC codes, and completely custom fields. Applications like MusicBrainz Picard, beets, and foobar2000 have full Vorbis Comment support and can automatically tag large FLAC libraries from online databases.
Building a FLAC Archive: Practical Recommendations
A well-organised FLAC library should follow consistent conventions: one album per folder, files named TrackNumber - Title.flac, embedded album art at 600×600 pixels or larger, and a separate cover.jpg in each folder for media server compatibility. Always keep your original WAV or CD rip — use FLAC as the archive format, and generate lossy copies (AAC 256k, MP3 320k) as needed for portable devices. A lossless archive is only valuable if you can always re-derive other formats from it.