Chmod Calculator

About Chmod Calculator

Calculates Unix file permission values visually using a checkbox grid. The grid maps to the three permission classes (Owner, Group, Other) across three permission types (Read, Write, Execute). Toggle any checkbox and both the octal number (e.g., 755) and symbolic notation (rwxr-xr-x) update instantly in both directions — you can also type an octal value or symbolic string and the checkboxes update to match. The octal format is a compact representation where each digit is the sum of Read (4), Write (2), and Execute (1) for that class. So 7 means all three permissions set, 5 means read+execute, 4 means read-only, 0 means no permissions. The symbolic format uses r for read, w for write, x for execute, and - for absence, displayed in owner/group/other order. Common permission values and when to use them: 755 (rwxr-xr-x) for directories and scripts — owner can do anything, everyone else can read and traverse. 644 (rw-r--r--) for regular files — owner can read and write, everyone else read-only. 600 (rw-------) for private files like SSH keys. 700 (rwx------) for private executables. 777 (rwxrwxrwx) gives everyone full access — avoid this in production as it is a common security misconfiguration. The setuid, setgid, and sticky bits are shown when a four-digit octal is entered.

How to Use Chmod Calculator Online

1. Paste your data into the input field above
2. The result appears instantly in the output area
3. Click "Copy" to copy the result to your clipboard

Visual Unix file permission calculator with octal and symbolic notation. Runs 100% client-side — no data is sent to any server.

Frequently Asked Questions