Linux Permission Octal Calculator
Toggle read, write and execute for owner, group and others. The octal number, symbolic notation and chmod command update live, or type an octal value to see which boxes it turns on.
Replace filename with your file name. Add -R after chmod to apply to a folder and everything inside it.
| Octal | Symbolic | Used for |
|---|---|---|
| 644 | rw-r--r-- | Regular files like documents and config files |
| 755 | rwxr-xr-x | Scripts and programs that must run |
| 600 | rw------- | Private files only the owner may read, like SSH keys |
| 700 | rwx------ | Private folders and scripts only the owner may use |
| 777 | rwxrwxrwx | Dangerous, everyone has full access, avoid |
Every file on Linux has 9 permission bits: read, write and execute for the owner, the group, and everyone else.
- Read is worth 4, write is worth 2, execute is worth 1. Add the values in each column to get one octal digit: read plus execute is 4 plus 1, which is 5.
- The three columns (owner, group, others) become three digits, for example 755.
- Symbolic notation writes the same thing with letters: rwx for full access, a dash - where a permission is missing, like rwxr-xr-x for 755.
- Reverse mode does the math backwards: each octal digit is split into its 4, 2 and 1 parts and the matching boxes are checked.
- The chmod command applies the number to a file: chmod 755 script.sh makes a script readable and runnable by everyone but changeable only by the owner.
This calculator works fully in your browser. No data is sent anywhere.
Frequently Asked Questions (FAQ)
What does the Linux Permission Octal Calculator do?
Toggle read, write and execute for owner, group and others, and the octal number, symbolic notation and chmod command update live. It also works in reverse: type an octal value to see which boxes it turns on.
What do I need to enter?
No typing is needed. Click the checkboxes, use a preset like 644, 755, 600, 700 or 777, or type a 3-digit octal value in reverse mode.
Why does the tool warn about 777?
777 gives everyone full read, write and execute access, so anyone on the system can read, change or delete the file. The page marks it dangerous and advises avoiding it.
What does the reverse mode do?
Type an octal value such as 755 in the reverse-mode box and the checkboxes update to show exactly which permissions it turns on.