🔐 Chmod Calculator
Calculate Unix file permissions
Owner
Group
Others
Result
Numeric
000
Symbolic
Calculate Unix file permissions
File permissions confuse beginners and still trip experienced admins when scripts mix octal (`755`) with symbolic (`u+x`). This page helps you translate, reason about owner/group/other bits, and avoid accidental world-writable files.
Calculate Unix file permissions with interactive checkboxes. Convert between symbolic and numeric notation.
Chief Technical Editor
File permissions confuse beginners and still trip experienced admins when scripts mix octal (`755`) with symbolic (`u+x`). This page helps you translate, reason about owner/group/other bits, and avoid accidental world-writable files.
It is useful when reading deployment docs, Dockerfiles, CI logs, or `ls -l` output and you need to be sure what a permission string actually allows.
Use it while learning Unix permissions, auditing scripts, or standardizing permission lines across a team runbook.
A Dockerfile uses `COPY --chmod=644` for a config. The developer checks what that means (rw-r--r--) and confirms the service user can still read but not execute the file.
Explicit permission math prevents “it worked on my machine” security holes in shared images.
Permissions combine read (4), write (2), execute (1) per class: user, group, others.
Symbolic notation expresses diffs (`+x`) while octal expresses full mode — know which your tool expects.
Remember directories need execute bit to enter; a common mistake is 644 on a directory that must be traversed.
Owner: read+write+execute (7), group and others: read+execute (5).
Any local user or compromised process may change or run the file.
A mask subtracted from default creation modes; your shell and app set it.
Learn both. Octal is common in scripts; symbolic is expressive for incremental changes.
No. This page explains and converts; you still apply modes with your OS tools.
ACLs extend POSIX permissions; this calculator focuses on classic mode bits.
Longer explanations that complement this calculator—same privacy-first, editorial tone.
A plain-language subnetting guide for students, admins, and certification prep when you need the math to click quickly.
A straightforward overview of client-side tools, optional Google ads, and how that maps to everyday privacy expectations.
Adjacent topic when verifying downloaded archives or permission-sensitive deploy artifacts.
Explore Tool »Often used alongside deploy scripts that set file modes and scheduled jobs.
Explore Tool »Helpful when log lines include permission strings you need to parse or scrub.
Explore Tool »