Audacity's FLAC export lets you pick a compression level from 0 to 8, and the official manual is unusually blunt about what climbing that slider buys you: files at level 8 are "rarely more than a few percent smaller" than files at level 0, but encoding them "can take three or four times longer."
Most pages about this setting just list the nine options. Audacity's own documentation already did the cost-benefit for you. This guide walks the export, tells you which level to choose, and points at the setting in the same dialog that moves file size far more than the level ever will.
Before you start
You do not need FFmpeg for FLAC. The manual's FAQ on opening and saving files states the shipped capability directly: "Audacity as shipped can import or export the following audio formats:" — and under "Compressed audio formats" it lists "Ogg Vorbis, FLAC and MP2." Nothing to install, on any platform.
Know roughly what you are about to write to disk. The FLAC export page describes the format's footprint this way: "The files it produces are about half as large as the uncompressed WAV or AIFF formats, but larger than compressed, lossy formats." Audacity's format comparison table puts numbers on that for 16-bit FLAC: 2.5 MB per minute mono and 5.0 MB per minute stereo — measured, in the manual's own words, "at default Audacity settings (that is, 44,100 Hz sample rate and default bit rate or quality settings in the case of compressed formats)." The same table note adds the caveat that matters here: "Where VBR compression is employed, the achieved size will vary depending on the content." FLAC is listed as a VBR format, so those are typical sizes, not guarantees.
Check your channel count before you commit. Audacity's Advanced Mixing Options page caps FLAC at "8 output channels (FLAC)" — lower than the 32 it allows for WAV, AIFF or OGG.
What the compression level actually changes
Here is the manual's description of the setting, in full:
"The level settings range from 0 to 8. Level 0 is optimized to encode as fast as possible. Level 8 is optimized to pack as efficiently as possible, so produces slightly smaller files than level 0 at the expense of taking longer to encode. Files encoded at level 8 are rarely more than a few percent smaller than those encoded at level 0, but can take three or four times longer to encode."
Three things follow from that paragraph.
The level is a packing setting, not a quality setting. Audacity's format table lists FLAC under "Lossy: No," and the description above frames the difference between 0 and 8 purely in terms of encoding speed and file size. Nobody is trading away audio to encode faster.
The top of the range is a bad default. A few percent, in exchange for three to four times the encode time, is a poor deal on anything you export regularly — a podcast master, a session bounce, a batch of tracks you are about to edit again. Sitting low on the scale costs you almost nothing.
Level 8 is only worth it when encoding time is a one-off. Compressing a library once, to sit on a drive for years? A few percent across hundreds of files is real, and you pay the encode cost once. Everything else: stay low.
The setting that moves size far more than the level does
In the same FLAC options panel, one row above, is the bit depth choice. The manual: "Choose from 16-bit (default) or 24-bit (approximately 50% larger file size)."
Read those two numbers side by side. The level slider is worth a few percent. The bit depth toggle is worth roughly fifty. If your FLAC files are bigger than you expected, look at bit depth first — chasing level 8 is optimizing the smaller of the two levers by an order of magnitude.
Keep 16-bit unless you have a reason to carry 24 (a 24-bit source you intend to keep editing, for example). It is the manual's stated default and it is what the 2.5 / 5.0 MB-per-minute figures above are based on.
Step by step: exporting FLAC
Step 1 — Unmute what you want exported. Audacity's export dialog documentation is explicit: "When using Export Audacity will only export tracks that are not grayed-out by use of the Mute or Solo buttons in the tracks' Track Control Panels." It also notes that "any hidden parts of audio clips are not exported." A soloed track quietly excludes everything else.
Step 2 — Open the export dialog with File > Export Audio (Ctrl + Shift + E). This is the single entry point the manual documents; every per-format options page in the manual describes the same route, choosing the format from the Format dropdown to reveal that format's options.
Step 3 — Pick FLAC, then set bit depth (16-bit unless you need 24) and the level (low, per the section above).
Step 4 — Set Channels deliberately. The dialog's default is described verbatim as "Stereo: stereo pair with left and right channels - this is the default setting even if you only have mono tracks for exporting." For a mono voice recording that default roughly doubles your file — the format table's 5.0 MB stereo versus 2.5 MB mono per minute is exactly that gap.
Step 5 — Export, and know your two buttons. "Stop button will halt the export where it is now, leaving the partially exported file in place," while "Cancel button will abort the export leaving no exported audio file." If you stop a slow level-8 encode partway, there is a half-written file on disk to clean up.
When what you actually need is an MP3
FLAC is the right container for a master. It is the wrong one for emailing a rough mix to a bandmate — it is, by the manual's own comparison, larger than the lossy formats. Audacity's MP3 guidance recommends exactly this split: "never do production work in MP3, instead work with a lossless format such as WAV, AIFF or FLAC and for final use then export to MP3."
If the FLAC already exists, you do not need to re-open the project to make that lossy copy:
Try it right here
Runs in your browser. Your file is not uploaded anywhere.
It runs in your browser tab — the file is read from disk, converted locally and handed back, never uploaded. Useful when the FLAC came from someone else, or you are on a machine without Audacity. WAV to MP3 works the same way; the rest are in all Clapr tools.
Common mistakes
- Reaching for level 8 by reflex. A few percent smaller, three to four times slower. Do it once for an archive, not every session.
- Exporting 24-bit "just to be safe." That is the "approximately 50% larger file size" option, and it is a far bigger size decision than the level.
- Leaving Channels on Stereo for a mono recording. The dialog defaults to stereo even when every track is mono.
- Exporting a long FLAC to a FAT or FAT32 drive. Those drives "are subject to a 4GB limit for any single file," and the manual confirms "the 4GB limit also applies to such exports." Reformat to exFAT or export elsewhere — the same trap that bites WAV exports over 4GB.
- Expecting artwork to survive. The manual states, for all formats: "Audacity currently discards any existing lyrics or album art when exporting."
FAQ
What is the best FLAC compression level in Audacity? A low one, for almost everybody. The manual states that level 8 files are "rarely more than a few percent smaller" than level 0 files while taking "three or four times longer to encode." Reserve the high end for one-time archival batches where encode time no longer matters.
Does a higher FLAC compression level reduce audio quality? No. Audacity's format table lists FLAC under "Lossy: No," and the manual describes the level purely as a trade between encoding speed and how efficiently the data is packed.
How much smaller is level 8 than level 0? "Rarely more than a few percent," in the manual's words. It gives no per-level figures beyond that, so treat any table of exact percentages you find elsewhere with suspicion.
Why is my FLAC so much bigger than an MP3 of the same audio? Because it is lossless. The manual puts FLAC at "about half as large as the uncompressed WAV or AIFF formats, but larger than compressed, lossy formats" — roughly 5.0 MB per minute for 16-bit stereo at default settings. For sharing, export or convert a lossy copy.
Do I need FFmpeg or LAME to export FLAC? No. FLAC is one of the formats Audacity can "import or export" as shipped, alongside Ogg Vorbis and MP2. FFmpeg is required for other formats, not this one.
Can Audacity export a 5.1 FLAC? It documents a ceiling of "8 output channels (FLAC)" in Advanced Mixing Options, so 5.1 is inside that limit. For multi-channel work generally, check the current behaviour in the official Audacity Manual before relying on a channel layout.
Working through other Audacity export quirks? The MP3 silence at the start of exports is the next one people hit — and there are more walkthroughs in our how-to guides.
All settings and quoted text above come from the Audacity Manual at manual.audacityteam.org (FLAC Export Options, Export Audio Dialog, Export Formats supported by Audacity, Advanced Mixing Options), checked 16 September 2026. Verify against the current manual before relying on any of it.
