Chmod Calculator

Interactive chmod permission calculator for Unix/Linux file permissions

Last updated: October 14, 2026

Select Permissions

owner

group

others

Results

Numeric Notation
644
Symbolic Notation
rw-r--r--
Command
chmod 644 filename
Description

Owner can read, write. Group can read. Others can read.

Understanding Chmod

  • Owner: The user who owns the file
  • Group: Users in the file's group
  • Others: All other users
  • Read (4): View file contents or list directory
  • Write (2): Modify file or add/remove files in directory
  • Execute (1): Run file as program or access directory
  • Common permissions: 644 (rw-r--r--) for files, 755 (rwxr-xr-x) for directories

Result actions

Copy or download the tool output, or share a link to Chmod Calculator.

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What this chmod calculator does

Select read, write, and execute permissions for the owner, group, and others. The calculator converts those nine standard permission bits to a three-digit octal value and symbolic rwx notation, then builds a command such as chmod 644 filename.

How octal permissions work

For each user class, read is 4, write is 2, and execute is 1. Add the selected values to get that class's digit: for example, read plus write is 6 (rw-), while read plus execute is 5 (r-x). The three digits are ordered owner, group, then others.

Use the calculator

  1. Select the permissions for each class using the checkboxes, or enter a three-digit octal value.
  2. Review the symbolic string, numeric value, and generated command.
  3. Copy the value or command and replace filename with your path before using it.

Scope and caution

This tool covers only the nine ordinary rwx bits, with values from 000 through 777. It does not calculate setuid, setgid, or sticky bits, ACLs, ownership, or the effective permissions produced by a particular filesystem. Check the target path and security implications before running a chmod command. Calculations happen locally in your browser.