Chmod Calculator

chmod Calculator — Overview

The chmod Calculator simplifies Unix and Linux file permission management by translating between human-readable checkboxes and the numeric octal codes used by the chmod command. Every file on a Unix system has three permission sets — Owner, Group, and Others — each with three possible permissions: read (r, value 4), write (w, value 2), and execute (x, value 1). These add up to a three-digit octal number like 755 or 644 that is passed to chmod. Remembering and mentally computing these values is error-prone, especially for less common combinations. This tool lets you tick checkboxes for the permissions you want, instantly shows the resulting numeric code and symbolic notation (e.g., rwxr-xr-x), and lets you type a number to decode existing permissions — making it useful for both setting and understanding file access controls.

Common Use Cases

• Setting correct permissions for web server files (e.g., 644 for files, 755 for directories)
• Decoding an unfamiliar permission number found in documentation or a server config
• Learning Unix permission concepts through a visual checkbox interface
• Quickly generating the right chmod command for scripts and deployment tasks

How to Use This Tool

Check or uncheck the read, write, and execute boxes for Owner, Group, and Others. The octal code, symbolic notation, and ready-to-use chmod command update instantly. Alternatively, type a known permission number into the numeric field to decode it into its checkbox representation.