What is a TMP file?

TMP (Temporary) files are created by applications and the operating system during normal operation. They serve as scratch space for data processing, crash recovery, and caching. TMP files are generally safe to delete when their parent application is closed, though deleting them while the creating application is running can cause errors or data loss.

The .tmp extension is a convention — not a standard. Any application can create a .tmp file with any internal structure. These files accumulate over time and can consume significant disk space, which is why tools like Windows Disk Cleanup and macOS storage management include dedicated options for removing temporary files.

How to open TMP files

• Depends on the creating application — the content type is not standardized
• Notepad / VS Code — Try opening as text; useful if the TMP file contains recoverable document content
• Rename the extension — If you know the source program, try changing .tmp to the expected format (e.g., .docx, .xlsx)
• Disk Cleanup (Windows) — Safely remove accumulated temp files system-wide
• HxD — Inspect binary content with a hex editor to determine the true format

Technical specifications

Common use cases

• Application caching: Office applications create TMP files during document editing as a buffer before saving to the final file
• Crash recovery: Microsoft Word’s auto-recovery feature stores unsaved work in .tmp files in the %TEMP% folder
• Print spooling: Windows creates TMP files in the print queue while documents wait to be printed
• Software updates: Installers download update packages as .tmp files before renaming them after verification
• Video and audio processing: FFmpeg, Premiere Pro, and other media tools create large .tmp files during transcoding and rendering

Where temporary files are stored

On Windows, the %TEMP% environment variable points to the current user’s temp folder. You can open it quickly by pressing Win + R and typing %temp%.

When are TMP files safe to delete?

TMP files are safe to delete when:

• The application that created them is fully closed
• The file’s last-modified date is more than a few days old
• The file name matches patterns like ~DF, tmp, or random alphanumeric strings

Do not delete TMP files while their parent application is open — this can cause crashes, lost data, or corrupted output files. Video editors and databases in particular may be actively writing to multi-gigabyte TMP files during operation.

Recovering content from TMP files

If an application crashed before saving, its TMP files may contain recoverable content:

1. Microsoft Word / Excel: Check %TEMP% for files named ~WRL*.tmp or ~WRF*.tmp — try renaming to .docx or .xlsx
2. Notepad: Unsaved Notepad content in Windows 11 is auto-saved separately, but older versions may leave TMP fragments
3. Video editors: Partial renders may be salvageable by renaming to the expected output format and opening in VLC

Disk space management

Accumulated TMP files are a common cause of low-disk-space warnings. On Windows, run Disk Cleanup (cleanmgr.exe) and select “Temporary files” to reclaim space. On Linux, /tmp is typically mounted on a tmpfs filesystem and cleared automatically at reboot. On macOS, temporary files are managed automatically by the system, though developer tools like Xcode can accumulate gigabytes of derived data in cache folders.