Chmod Calculator
Convert Unix file permission symbols (e.g., rwxr-xr-x) to numeric mode (e.g., 755) and vice versa. Understand permission bits and calculate octal values.
Published by:
isCalculator Editorial Team
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How to Use the Chmod Calculator
This calculator converts between symbolic (e.g., rwxr-xr-x) and numeric (e.g., 755) Unix file permission modes. Follow these steps:
- Enter a permission mode in either the Symbolic Mode field (exactly 9 characters using
r,w,x,-) or the Numeric Mode field (3 or 4 digits, each 0–7). - Click "Convert" (or press Enter). The calculator will automatically convert to the other format and display the result.
- View the result in the green box. A breakdown shows owner, group, and other permissions with their numeric values.
- Use "Swap" to clear both fields and start over.
Tip: For 4-digit numeric modes (e.g., 0755), the first digit is ignored—only the last three are used.
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Frequently Asked Questions
Chmod (change mode) is a Unix command that changes the permissions of a file or directory. Permissions define who can read, write, or execute a file.
Symbolic permissions consist of three groups of three characters: owner (rwx), group (r-x), and others (r-x). Each character indicates read (r), write (w), execute (x), or no permission (-).
Numeric permissions are three digits (0-7). Each digit sums the permissions: 4 for read, 2 for write, 1 for execute. For example, 755 means owner has rwx (7), group has r-x (5), others have r-x (5).
