What do the octal digits mean?

Each digit (0-7) sums three permission bits: Read=4, Write=2, Execute=1. For example, 7 = 4+2+1 (full access), 5 = 4+0+1 (read+execute), 6 = 4+2+0 (read+write).

What does chmod 755 mean?

Owner gets read+write+execute (7), Group gets read+execute (5), and Public gets read+execute (5). This is a common permission for directories and executable files.

What does chmod 644 mean?

Owner gets read+write (6), Group gets read-only (4), and Public gets read-only (4). This is the standard permission for regular files like documents and images.

Chmod Calculator

Toggle checkboxes for Owner, Group, and Public permissions to instantly see the octal value, symbolic notation, and chmod command.

import CopyButton from "./_CopyButton.astro"

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How to use Chmod Calculator

Check or uncheck the Read, Write, and Execute boxes for Owner, Group, and Public.
Read the octal result and the corresponding chmod command.
Click the Copy button to copy the chmod command to your clipboard.

What is Chmod Calculator?

Chmod (change mode) is a Linux/Unix command that sets file permissions using an octal (base-8) number. Each digit controls a permission set: Owner, Group, and Others (Public). Each digit is the sum of Read (4), Write (2), and Execute (1). For example, 755 gives the owner full access and everyone else read+execute.

This interactive calculator lets you toggle permissions visually and copies the exact chmod command. It's ideal for developers configuring web server permissions, sysadmins setting up file access, and anyone learning Unix permissions.

FAQ

What do the octal digits mean?: Each digit (0-7) sums three permission bits: Read=4, Write=2, Execute=1. For example, 7 = 4+2+1 (full access), 5 = 4+0+1 (read+execute), 6 = 4+2+0 (read+write).
What does chmod 755 mean?: Owner gets read+write+execute (7), Group gets read+execute (5), and Public gets read+execute (5). This is a common permission for directories and executable files.
What does chmod 644 mean?: Owner gets read+write (6), Group gets read-only (4), and Public gets read-only (4). This is the standard permission for regular files like documents and images.

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Chmod Calculator

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