Chmod Calculator
Tick read, write and execute boxes to get the octal, symbolic and chmod command for any file permission.
| Who | Read (4) | Write (2) | Execute (1) |
|---|---|---|---|
| Owner (u) | |||
| Group (g) | |||
| Others (o) |
What these permissions allow
How it works
Tick the read, write and execute boxes for the owner, the group and everyone else and the
chmod calculator instantly shows the matching octal value (like 644 or
755), the symbolic notation (rw-r--r--) and a ready-to-paste
chmod command. Read is worth 4, write 2 and execute 1, so each digit is just the
sum of the permissions for that class of user — that is why 4+2+1 = 7 means full access.
The conversion works both ways: type an octal value or a symbolic string and the checkboxes
update to match. Optional setuid, setgid and sticky bits add the fourth leading digit, and
the -R switch makes the command apply to a whole folder tree.
Everything is calculated in your browser with JavaScript — nothing is uploaded, so it is safe
to use with real server paths.
Frequently asked questions
What does chmod 755 mean?
755 means the owner can read, write and execute (7 = 4+2+1) while the group and everyone else can only read and execute (5 = 4+1). In symbolic notation that is rwxr-xr-x. It is the usual setting for folders and for scripts or programs that need to be runnable by anyone but only editable by their owner.
What does chmod 644 mean, and when should I use it?
644 gives the owner read and write access (6 = 4+2) and gives the group and others read-only access (4), or rw-r--r-- symbolically. It is the standard permission for regular files such as HTML, CSS, images and config files on a web server, because nobody except the owner can modify them and nothing is marked executable.
How do I convert octal permissions to symbolic notation and back?
Each octal digit is the sum of read (4), write (2) and execute (1) for one class of user — owner, group, then others — so 6 becomes rw- and 5 becomes r-x. This calculator does it both ways: type 755 to see rwxr-xr-x, or paste rwxr-xr-x (a leading file-type character like -, d or l is fine) to get 755. A leading fourth digit covers setuid (4000), setgid (2000) and the sticky bit (1000).