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chmod Permissions Calculator

Check the read/write/execute boxes for owner, group and others to instantly calculate octal (755), symbolic (rwxr-xr-x) and chmod commands. Special bits supported.

Last updated: 2026/10/16 Developer Feedback & bug reports

Permission Settings

Who Read (r) Write (w) Execute (x)
Owner (u)
Group (g)
Others (o)
Special Bits

Common Presets

Octal 644
Symbolic rw-r--r--
chmod command (numeric) chmod 644 filename
chmod command (symbolic) chmod u=rw,g=r,o=r filename

How to Use

1

Check Permissions

Toggle the read, write and execute checkboxes for owner, group and others.

2

View Results

Octal (755), symbolic (rwxr-xr-x) and chmod commands are calculated instantly. You can also type an octal value to reverse it.

3

Copy the Command

Copy the generated chmod command and paste it straight into your terminal.

About the chmod Permissions Calculator

A tool that converts Unix file permissions (Linux, macOS, etc.) between three formats: checkboxes, octal numbers and symbolic notation. It shows at a glance how numeric values like chmod 755 map to symbolic strings like rwxr-xr-x, and fully supports setuid, setgid and sticky special bits. All calculations run in your browser and nothing is ever sent to a server.

Features

  • Intuitive CheckboxesJust toggle 9 checkboxes to set permissions. Everything works with a mouse.
  • Three-way ConversionOctal (755), symbolic (rwxr-xr-x) and chmod commands are shown together in real time.
  • Special Bits SupportAccurately calculates 4-digit octal values (such as 4755) including setuid, setgid and sticky bits.
  • Fully In-BrowserAll calculations run locally in your browser. Nothing is sent to any server.

Use Cases

  • Setting web server file and directory permissions (644, 755, etc.)
  • Adding execute permission to shell scripts (chmod +x)
  • Setting SSH key file permissions to 600
  • Applying the sticky bit to shared directories (1777)
  • Learning, teaching and certification exam prep on permissions

FAQ

What do the permission numbers (like 755) mean?
Each digit represents the permissions for owner, group and others, as the sum of read=4, write=2 and execute=1. For example, 7 (4+2+1) means read, write and execute, while 5 (4+1) means read and execute. So 755 gives the owner rwx and group/others r-x.
What is the difference between 644 and 755?
644 (rw-r--r--) suits regular files: the owner can write, everyone else can only read. 755 (rwxr-xr-x) suits directories and executables: the owner has read/write/execute, others have read and execute. Directories need the execute (x) bit to be entered.
What are setuid, setgid and the sticky bit?
These are special bits set in the leading (4th) octal digit. setuid (4) runs a program with the owner's privileges, setgid (2) runs with the group's privileges or makes new files inherit the directory group, and sticky (1) restricts file deletion in a directory to the file owner. The classic example is 1777 on /tmp.
What do the letters s and t mean in symbolic notation?
They are special bits shown in the execute position. Lowercase s/t means execute permission is set AND the special bit is on; uppercase S/T means the special bit is on but execute is off. For example rwsr-xr-x has setuid, and rwxr-xr-t has the sticky bit.
Is any data I enter sent anywhere?
No. All calculations run entirely in your browser with JavaScript, and nothing you enter is ever sent to or stored on a server. It is completely private.

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