What FLAC is
FLAC stands for Free Lossless Audio Codec. It compresses audio the way a ZIP file compresses documents: the data gets smaller, and when the file is played back, every original sample comes out exactly as it went in. That is what lossless means, and it is the main difference from MP3 or AAC, which permanently discard some detail.
Because the compression does not remove anything, a FLAC file is larger than an MP3 but typically noticeably smaller than the equivalent uncompressed WAV. It is a favorite for music libraries, archiving, and careful listening.
Why people convert audio to FLAC
The most common reason is storage. If you have a collection of WAV recordings, packing them as FLAC saves space without changing the sound at all. It is also a sensible archive format for recordings you may want to process or re-export later, since you will not lose quality by storing them this way.
There is one thing FLAC cannot do. If your source is already an MP3 or AAC file, converting it to FLAC does not restore what compression removed. You will get a lossless copy of a lossy recording, which is bigger than the original but not better. For a smaller, more shareable file, use the AAC Converter or the MP3 Converter instead.
How to convert audio to FLAC with this tool
- Drag your audio file onto the drop area, or click it to select one.
- The file name and size are shown. There are no settings to choose for FLAC.
- Click Run. The first run downloads the ffmpeg engine (roughly 30MB) and shows a progress bar, so allow some extra time.
- Listen to the result in the player that appears.
- Click Download. The file is saved as your original name plus "-convert", ending in
.flac. - Click Start over to load a different file.
Everything happens locally in the browser through ffmpeg.wasm, so the audio is not uploaded.
Practical notes and limits
The tool uses the encoder's default compression level and offers no controls for bit depth, sample rate, or compression effort. The result is a standard FLAC file, but if you need a specific specification for mastering or distribution, use dedicated audio software.
Do not expect the file to be dramatically smaller than the source if it is already compressed, and do not be surprised if it is larger. A lossless copy of a lossy file keeps the lossy file's limits and adds the size of lossless storage.
Very long recordings are processed in browser memory and may be slow on modest hardware. If you see "Couldn't process this audio file.", try a shorter section. Need a lossless but uncompressed result instead, for editing software that prefers it? The WAV Converter covers that.