Octal Permission Calculator
Select read, write and execute access for owner, group and others to compute the resulting chmod octal code.
Inputs
Octal Code
754
Symbolic Mode
rwxr-xr--
chmod Command
chmod 754 filename
Owner Digit
7
Group Digit
5
Others Digit
4
Step by step
Values used
Owner Read = Yes; Owner Write = Yes; Owner Execute = Yes; Group Read = Yes; Group Write = No; Group Execute = Yes; Others Read = Yes; Others Write = No; Others Execute = No
Octal digit from bits
digit = 4×read + 2×write + 1×execute
Octal Code
= 754
Symbolic Mode
= rwxr-xr--
chmod Command
= chmod 754 filename
Owner Digit
= 7
Group Digit
= 5
Others Digit
= 4
How it works
Each octal permission digit is the sum of read (4), write (2) and execute (1) for that class of user. Toggling the checkboxes for owner, group and others rebuilds each digit from the checked bits, producing both the 3-digit octal code and the equivalent symbolic string, plus a ready-to-run chmod command.
Formula
Octal digit from bits
digit = 4×read + 2×write + 1×execute
- r
- 1 if read checked
- w
- 1 if write checked
- x
- 1 if execute checked
Frequently Asked Questions
Why is read worth 4, write worth 2 and execute worth 1?
These are powers of two (2^2, 2^1, 2^0), so any combination of the three permissions maps to a unique digit from 0 to 7, exactly matching a 3-bit binary value.
What is the most common octal code for scripts?
755 (rwxr-xr-x) is common for executable scripts and directories: the owner gets full control while group and others can read and execute but not modify.
What is the most common octal code for regular files?
644 (rw-r--r--) is typical for regular files: the owner can read and write, while group and others can only read.