Online Linux Chmod Calculator

Calculate chmod permissions, octal notations, symbolic codes, and generate bash commands with a visual interactive matrix. 100% private in-browser tool.

At a glance

Linux Chmod Permissions Calculator is a free browser tool that calculates Linux chmod permissions, octal codes, symbolic notation, and SUID/SGID special bits. Full support for SetUID (4000), SetGID (2000), and Sticky Bit (1000). All processing is local: nothing is uploaded, and no account is required.

Developer Suite: Chmod Calculator SQL Formatter HTML Minifier CSS Minifier JSON Diff Regex Tester

100% In-Browser Bitmask Logic

Octal values, POSIX permission bits, and bash commands are calculated instantly in client-side memory. Zero server transmission.

Pure In-Browser

Standard Presets:

Octal Permission Value 3-digit & 4-digit notation

chmod

(0755)

Type any 3 or 4-digit octal to sync

Symbolic POSIX Notation

File (-) Dir (d)

Owner: rwx • Group: r-x • Others: r-x

Interactive Permissions Checkbox Matrix

Click checkboxes to toggle bits

Role Scope	Read (r) Value: 4	Write (w) Value: 2	Execute (x) Value: 1	Subtotal
Owner (u)				7
Group (g)				5
Others / Public (o)				5

Special Execution Modes Special Octal: 0

SetUID (4000)

Run binary with owner privileges (s/S)

SetGID (2000)

Run with group / inherit directory group

Sticky Bit (1000)

Only owner or root can delete files (t/T)

Linux Terminal Command Builder Apply Recursively (-R)

Target Path:

chmod 755 /var/www/html

chmod u=rwx,g=rx,o=rx /var/www/html

Plain-English Permission Breakdown

How Octal Math Works

Linux file modes are 3-bit binary masks for each scope: Read = 4 (100), Write = 2 (010), and Execute = 1 (001). Summing them creates values 0 through 7.

Why SSH Keys Need 600 or 400

OpenSSH refuses to connect if private keys (like ~/.ssh/id_rsa) are readable by group or others. Running chmod 600 ensures that only the file owner can read or write the secret.

Directories Need Execute (+x)

In Unix, the execute bit on directories allows users to traverse into the folder (cd) and access its subfiles. A directory with only read permission allows listing filenames but blocks viewing file contents or metadata.

Why Use This Linux Chmod Permissions Calculator?

Interactive Checkbox Matrix: Instantly toggle Read (4), Write (2), and Execute (1) bits for Owner, Group, and Others.

Bidirectional Octal & Symbolic Sync: Type any 3 or 4-digit octal value or symbolic string to synchronize matrix checkboxes.

Special Permission Modes: Full support for SetUID (4000), SetGID (2000), and Sticky Bit (1000).

Terminal Command Builder: Generates both numeric (chmod 755) and symbolic (chmod u=rwx...) commands with -R recursive support.

Plain-English Explanation: Explains precisely what each role can and cannot perform on the file or directory.

100% Client-Side Privacy: All bitwise permission logic executes entirely in your local browser memory.

How to Use Linux Chmod Permissions Calculator

Select Permissions or Preset

Click checkboxes in the matrix, type an octal number (e.g., 755, 644), or click a preset button.

Configure Target Path and Options

Enter the target file or directory path and optionally enable the -R recursive flag.

Copy Generated Command

One-click copy the numeric or symbolic chmod command directly into your terminal.

Script Permissions: Octal 755 Maps to rwxr-xr-x

The engine converts each scope with Read=4, Write=2, Execute=1 bitmask sums into octal and POSIX symbolic notation, rendering bash commands client-side.

Octal and Checkbox Input Source

Octal: 755 (Owner rwx, Group r-x, Others r-x)  Target: deploy.sh

Symbolic Notation and Command Processed

Symbolic: rwxr-xr-x (-rwxr-xr-x). Command: chmod 755 deploy.sh

Technical Specifications & Engine Details

Technical specifications and engine details for Linux Chmod Permissions Calculator
Specification	Details
Supported Formats	Text / Input → TEXT
Execution Mode	100% Client-Side In-Browser (client)
Browser Requirements	Requires modern web browser with ECMAScript 6+ and standard DOM Web APIs.
Performance Constraints	Client browser memory limit (typically 1–2 GB RAM); processing speed depends on local device CPU.

Maintained by Pragyan Pahadi

100% Client-Side Privacy Guarantee

All chmod calculations and permission evaluations execute locally in your web browser. Zero commands or file paths are sent to external servers.

Frequently Asked Questions

How does octal permission calculation work in Linux?

Each scope (Owner, Group, Others) is represented by a 3-bit binary number where Read = 4, Write = 2, and Execute = 1. The sum of these values gives a single digit from 0 to 7 (e.g. Read + Write = 4 + 2 = 6).

What is the difference between chmod 755 and 644?

Chmod 644 gives the owner read/write access while group and others can only read; it is standard for regular files. Chmod 755 adds execute permissions for everyone, which is required for executable scripts and directories to allow folder traversal.

What are SUID, SGID, and the Sticky Bit?

These are special permission bits represented by a 4th leading octal digit: SetUID (4000) runs a binary with file owner rights, SetGID (2000) inherits group ownership, and the Sticky Bit (1000) prevents non-owners from deleting files in shared directories (like /tmp).

Is any command or file path sent to a remote server?

No. All bitmask calculations, string generation, and command building happen 100% in your local browser memory. No data is transmitted over the network.

Methodology

Rankings and recommendations here are never paid for.

Last updated October 2026.