Unix Permission Calculator for chmod Modes
Convert read, write, and execute bits into chmod octal modes, symbolic permissions, and command snippets.
A Unix permission calculator converts read, write, and execute bits into modes like 755 or 644.
Use it to understand chmod values before copying a command into a terminal.
Use known defaults carefully
644 is common for files, while 755 is common for executable directories or scripts.
Review before running
This page formats commands but does not check your filesystem or execute anything.
Try a common chmod setup
Valid 3-digit octal mode.
755
rwxr-xr-x
chmod 755 public
How the number is built
Read is 4, write is 2, and execute is 1. Add the enabled bits for owner, group, and others to get a three-digit mode.
Suggested workflow
Deployment sanity-check workflow
Calculate permissions, verify files, then keep scheduled maintenance config readable.
Related tools
Related developer tools
What does chmod 755 mean?
755 means owner can read, write, and execute, while group and others can read and execute.
What does chmod 644 mean?
644 means owner can read and write, while group and others can only read.
Does this tool run chmod commands?
No. It only calculates and formats permission values in the browser.
Does it need a backend?
No. Permission calculation is simple browser-side logic.