Chmod Calculator
Convert Unix file permissions between symbolic, octal and checkbox form.
Tick permissions or type an octal value — the symbolic string, octal number and chmod command update instantly.
| Who | Read (4) | Write (2) | Execute (1) |
|---|---|---|---|
| Owner | |||
| Group | |||
| Public |
| Symbolic | --------- |
|---|---|
| Octal | 000 |
| Command | chmod 000 file |
Frequently asked questions
What do the numbers in chmod 755 mean?
Each digit is a permission set for owner, group and others. It sums read (4), write (2) and execute (1): 7 = read+write+execute, 5 = read+execute. So 755 means the owner can do everything and everyone else can read and execute.
What is the difference between symbolic and octal?
Symbolic notation (rwxr-xr-x) shows each permission bit as a letter or dash; octal (755) encodes the same thing as three digits. This tool shows both and keeps them in sync.
What does execute permission mean on a folder?
On a directory, execute controls whether you can enter it and access files inside by name. A readable but non-executable directory lets you list names but not open the entries.
Is 777 safe to use?
Rarely. 777 lets anyone read, write and execute, which is a common security mistake on web servers. Prefer the least permission that works — often 644 for files and 755 for directories.
What are the leading-zero and fourth digit for?
An optional fourth leading digit sets special bits (setuid, setgid and the sticky bit). This calculator focuses on the standard three-digit owner/group/other permissions.