How to use the workspace
- Choose octal mode, permission checkboxes or symbolic changes.
- For symbolic changes, provide the starting mode and explicit u, g, o or a targets.
- Review both octal and symbolic results, especially special bits. Copy the command only after checking the file context.
A concrete starting point
0644 = rw-r--r-- u+x,g-w applied to 0644 gives owner execute permission r = 4, w = 2, x = 1
The workspace computes the exact result. No command is executed and no file permissions are changed.
Read the result carefully
The fourth octal digit represents setuid, setgid and sticky bits. Uppercase S or T indicates a special bit without the corresponding execute bit. Directory execute permission means traversal, not running a directory.
Common mistakes to avoid
- Permissions interact with ownership, ACLs and mount options beyond this calculator.
- Do not make a file world-writable simply to remove an access error.
- Conditional X and permission-class copying are outside this release; use explicit rwxst changes.
Limits & privacy
Three- or four-digit octal input. Symbolic expressions require explicit targets and +, - or =. This is a local calculator, not a shell.
Local: processed in this browser
Open Chmod Calculator →Inputs stay in browser memory. Saving or downloading is an explicit action; there is no automatic input history.
Read the full privacy boundaries