Audacity's "Disk full or not writable" error covers two different problems that share one message. The manual states it directly: "This error message is telling you that the disk you are using is full, or that the disk or file that you are trying to write to is write-protected."
That is worth reading twice, because a full disk and a write-protected destination need opposite responses, and the dialog does not tell you which one you hit.
What this error actually means
The error is not specific to exporting. Audacity's page for it lists the operations that can trigger it:
"Recording / Saving a project / Exporting from a project / Importing into a project / Applying effects / Editing"
Export is one of six. So if the message appears when you press Export, the disk pressure may have been building through the whole editing session — the export is just the moment Audacity finally needed more room than was available.
There is also an earlier warning you may have clicked past. Per the manual: "Audacity will warn on start up or when using File > New to create a new project if you have 100 MB or less space in the temporary folder for recording or editing." If you saw that warning at launch and kept going, this error is the follow-up.
Do the arithmetic before you start deleting things
This is where most advice on this error goes vague. Audacity's manual gives two hard numbers you can actually budget with.
The first: "As a guideline, one hour of stereo recording at default settings (44.1kHz, 32-bit) occupies approximately 1.2 GB of disk space".
The second puts the warning threshold in the same units: "100MB is approximately 5 minutes of stereo audio or 10 minutes of mono audio at default settings."
Two things follow from those figures, and both are the kind of detail that turns a mystery error into a planning problem:
- A one-hour stereo session is a multi-gigabyte commitment, not a few hundred megabytes. Recording a two-hour interview means budgeting on the order of the 1.2 GB per stereo hour figure, doubled — before any effects, undo headroom, or the exported file itself.
- Mono halves it. The 100 MB comparison is explicit that the same space holds twice as much mono audio as stereo. If the source is a single voice, recording or mixing to mono is the cheapest space saving available.
Note the qualifier in the first quote: those defaults are 44.1 kHz, 32-bit. That is the project side. The export side has a different default — Audacity's page on unsuitable drives says "The default export setting is 16-bit". Project bit depth and export bit depth are two separate settings, and confusing them is why people get two different size estimates for the same recording.
The fastest fix, and the one thing not to do
Free space on the drive Audacity is writing to. But the manual is specific about two ways of doing that which will make things worse:
"Do not delete the AUP3, WAL or (Windows only) SHM files for your project as part of this freeing up of space."
"Do not try to reduce space usage by deleting part of the project in Audacity, this will only try to take up more temporary space on the disk."
That second one is genuinely counterintuitive, and it is the reason people dig themselves deeper. The instinct when a disk is full is to throw away the audio you no longer need — trim the dead air, delete the failed take, then export. Audacity says that move does the opposite of what you expect: it asks for more temporary space, not less. Delete files from elsewhere on the disk instead, and leave the project untouched until the export succeeds.
The other lever is the format you export to. Audacity's format comparison table gives typical file sizes per minute at default settings — 10.0 MB per minute for stereo 16-bit PCM WAV, 5.0 MB for 16-bit FLAC, and 1.0 MB (CBR) for MP3. The table's own condition matters: those are "typical achieved mono and stereo file sizes with different formats at default Audacity settings (that is, 44,100 Hz sample rate and default bit rate or quality settings in the case of compressed formats)", and where VBR is used the achieved size varies with content.
If the export has to fit an email or a chat window, the same logic applies to any media file you are trying to send:
Try it right here
Runs in your browser. Your file is not uploaded anywhere.
Already exported a large WAV before the disk filled up? Converting it afterwards avoids re-exporting from the project at all — WAV to MP3 and FLAC to MP3 both run in your browser tab, so the file never gets uploaded anywhere.
If you are not sure which disk Audacity is filling, an unsaved project writes here:
Windows: C:\Users\<your username>\AppData\Local\Audacity\SessionData
macOS /Users/<your username>/Library/Application Support/SessionData
GNU/Linux: /var/tmp/audacity-<your username>One warning attached to that location: "If Audacity is closed before the project has been saved, the temporary project files will be automatically and permanently deleted." Do not close Audacity to "release" the space.
Other causes, in order of likelihood
The destination is write-protected. This is the second half of the official message and is easy to miss when the word "full" is right there. A read-only folder, a locked file, or a drive mounted read-only produces the same dialog on a disk with plenty of room.
The drive is formatted FAT or FAT32. Audacity's unsuitable drive page is blunt about this: "FAT and FAT32 formatted drives are subject to a 4GB limit for any single file". Exports are allowed to such drives, but "the 4GB limit also applies to such exports" — and critically, "In this case freeing up space will not work and you will need to Export to a non-FAT formatted drive." Two more details from the same page: "Clicking the OK will remove the partially exported file from your FAT/FAT32 drive", and "Audacity prevents you from saving a project using a FAT/FAT32 formatted drive". If your project lives on a USB stick, this is the first thing to check.
The WAV or AIFF itself is over 4 GB. This one behaves differently. Audacity "has a special trap for this case and does not even attempt to make the export", because "the forecasted size can be accurately calculated in advance, unlike with compressed file formats". At the 16-bit export default you get "about 6 hours 45 minutes of stereo audio for WAV and AIFF at Audacity's default settings" — versus about 3 hours 22 minutes at 32-bit, which is the project default. Same 4 GB ceiling, different bit depths, two different durations. For compressed formats the manual says "the maximum size will be much larger and unlikely to be an issue for most, if not all, users."
You got "Unable to export" with a code instead. Audacity's page for those messages points back here: "Some of these errors may have an underlying cause of disk full, so you may want to check your disk space and read Error: Disk full or not writable for guidance." The codes look like the manual's own example, OGG:355.
How to tell it worked
Check free space on the destination drive against the 1.2 GB per stereo hour guideline before retrying, not after. If the export completes but the file is suspiciously small, the export itself failed rather than the disk — that is a different problem, and other export and error fixes cover it.
FAQ
Why does Audacity say the disk is full when I have free space? Because the same message also covers a write-protected target. The manual's wording is "the disk you are using is full, or that the disk or file that you are trying to write to is write-protected." Check the folder's permissions and whether the drive is mounted read-only.
How much disk space does an hour of recording in Audacity need? Audacity's guideline is that "one hour of stereo recording at default settings (44.1kHz, 32-bit) occupies approximately 1.2 GB of disk space". Mono at the same settings uses roughly half, per the manual's note that 100 MB holds about 5 minutes of stereo or 10 minutes of mono.
Can I delete part of the project to free up space? No. Audacity says explicitly: "Do not try to reduce space usage by deleting part of the project in Audacity, this will only try to take up more temporary space on the disk." Free space elsewhere on the drive instead.
Which files should I never delete when clearing space? "Do not delete the AUP3, WAL or (Windows only) SHM files for your project as part of this freeing up of space." Those are your project.
Why does freeing up space not help on my USB drive? If it is FAT or FAT32, single files are capped at 4 GB regardless of free space, and the manual's instruction is to export to a non-FAT formatted drive.
Working with audio you need to move, convert, or shrink after export? Browse all Clapr tools — they run locally in your browser, so nothing is uploaded. Facts on this page are quoted from the official Audacity Manual pages for "Error: Disk full or not writable", "Error: Unsuitable drive", and the export format tables, checked 16 September 2026.
