How to Calculate Chmod Permissions: Formula, Steps & Examples
Learn how to calculate Chmod Permissions — the formula explained step by step, with worked examples and a free calculator to check your answer.
Chmod Permissions Calculator
Verified formula Updated Jun 2026 Private — runs on your device
Verified formula
Private
Octal permission code
755
For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.
How to use the Chmod Permissions Calculator
The Chmod Permissions Calculator works out your octal permission code in an instant. Enter owner read (1=yes), owner write (1=yes) and owner execute (1=yes) and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.
- Enter the owner read (1=yes).
- Enter the owner write (1=yes).
- Enter the owner execute (1=yes).
- Enter the group read (1=yes).
- Enter the group write (1=yes).
- Enter the group execute (1=yes).
- Enter the others read (1=yes).
- Enter the others write (1=yes).
- Enter the others execute (1=yes).
- Read off your octal permission code — the calculator updates automatically, with no button to press.
Formula
The Chmod Permissions Calculator uses the formula:
Octal permission code = (Owner read (1=yes) × 4 + Owner write (1=yes) × 2 + Owner execute (1=yes)) × 100 + (Group read (1=yes) × 4 + Group write (1=yes) × 2 + Group execute (1=yes)) × 10 + (Others read (1=yes) × 4 + Others write (1=yes) × 2 + Others execute (1=yes))
Worked example
For example, with owner read (1=yes) of 1, owner write (1=yes) of 1, owner execute (1=yes) of 1 and group read (1=yes) of 1 and the other inputs, the octal permission code is 755.
| Owner read (1=yes) | 1 |
|---|---|
| Owner write (1=yes) | 1 |
| Owner execute (1=yes) | 1 |
| Group read (1=yes) | 1 |
| Group write (1=yes) | 0 |
| Group execute (1=yes) | 1 |
| Others read (1=yes) | 1 |
| Others write (1=yes) | 0 |
| Others execute (1=yes) | 1 |
| Octal permission code | 755 |
|---|
Results are estimates for educational use, not professional advice.
Frequently asked questions
Each of owner, group and others gets a digit: read is 4, write is 2, execute is 1. Add the values you want. Read-write-execute is 7.
The owner has read, write and execute (7); group and others have read and execute (5). It is common for scripts and folders.
The owner can read and write (6); group and others can only read (4). It is typical for regular files.
Run the command chmod followed by the three-digit code and the file name, for example chmod 755 script.sh.
The Chmod Permissions Calculator uses the formula: Octal permission code = (Owner read (1=yes) × 4 + Owner write (1=yes) × 2 + Owner execute (1=yes)) × 100 + (Group read (1=yes) × 4 + Group write (1=yes) × 2 + Group execute (1=yes)) × 10 + (Others read (1=yes) × 4 + Others write (1=yes) × 2 + Others execute (1=yes)). For example, with owner read (1=yes) of 1, owner write (1=yes) of 1, owner execute (1=yes) of 1 and group read (1=yes) of 1 and the other inputs, the octal permission code is 755.
Enter the owner read (1=yes). Enter the owner write (1=yes). Enter the owner execute (1=yes). Enter the group read (1=yes). Enter the group write (1=yes). Enter the group execute (1=yes). Enter the others read (1=yes). Enter the others write (1=yes). Enter the others execute (1=yes). Read off your octal permission code — the calculator updates automatically, with no button to press.