How does chmod numeric mode work?

Each permission is a bit value: read = 4, write = 2, execute = 1. Add values for owner, group, and others to form modes like 755 or 644.

What are setuid, setgid, and sticky bits?

They are special permission bits represented by a leading octal digit. setuid = 4, setgid = 2, sticky = 1. Combined examples include 4755, 2755, and 1777.

What is the difference between symbolic and numeric chmod?

Numeric mode uses octal digits like 755. Symbolic mode uses expressions such as u=rwx,g=rx,o=rx or u+s for special bit changes.

Can I use this for files and directories?

Yes. The calculator helps for both files and directories, but always confirm security requirements before applying broad permissions on production systems.

Does this tool upload my permission data?

No. All calculations run locally in your browser and nothing is sent to a server.

Linux Permission Calculator (chmod)

Calculate chmod numeric and symbolic permissions from a visual rwx matrix. Toggle owner, group, others, and special bits to generate secure and accurate Linux file mode commands.

Toggle permissions for owner, group, and others to generate chmod numeric mode, symbolic mode, and Linux-style permission strings instantly.

Numeric Mode

755

Symbolic Mode

u=rwx,g=rx,o=rx

ls -l Format

-rwxr-xr-x

Command

chmod 755 filename

Type Numeric Mode (3 or 4 octal digits)

Special Bits

setuid (4)setgid (2)sticky (1)

Quick Presets

Features

Everything you need to calculate and apply Linux permissions correctly

Visual Permission Matrix

Toggle read, write, and execute bits for owner, group, and others in a clear checkbox table.

Numeric and Symbolic Output

Generate octal mode values like 755 and symbolic expressions like u=rwx,g=rx,o=rx instantly.

Special Bit Support

Include setuid, setgid, and sticky bits for advanced Linux permission scenarios.

Copy-Ready Commands

Copy generated chmod modes and command strings directly for shell usage and scripts.

Use Cases

Common Linux and DevOps scenarios where accurate chmod values matter

Deployment and CI scripts

Server hardening

Shared directories

Permission troubleshooting

About Linux Permission Calculator

Understand chmod permissions faster with visual mapping between bits and command syntax

How chmod values are calculated

Special bits explained

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Frequently Asked Questions

Quick answers about Linux file permissions and chmod notation

chmod 755 means owner has rwx permissions (7), while group and others have r-x permissions (5). It is commonly used for executable scripts and directories.

Use 644 for regular files that should not be executable. Use 755 only when execute permission is required, such as for scripts or directories.

Sticky bit on a directory allows users to create files but restricts deletion to the file owner, directory owner, or root. /tmp commonly uses mode 1777.

These letters indicate special bits in the execute positions. Lowercase means execute is also set; uppercase means execute is not set for that class.

Yes. The tool is free and runs directly in your browser.

Class	Read (4)	Write (2)	Execute (1)	Digit
Owner (u)				7
Group (g)				5
Others (o)				5