Unix file permissions calculator
Click the read, write, and execute checkboxes for owner, group, and other to build a Unix file permission set. The numeric octal value and symbolic notation update instantly.
| Read | Write | Execute | Value | |
|---|---|---|---|---|
| Owner | 7 (rwx) | |||
| Group | 5 (r-x) | |||
| Other | 5 (r-x) |
How it works
The tool converts between octal, symbolic, and binary permission representations using pure JavaScript bit arithmetic. No library required. Checking a box sets the corresponding bit; typing an octal value like 755 reverses the process to tick the right boxes.
Processing runs in your browser
All calculations happen locally in the page. Our servers are not involved at any point.
Related operations
For subnet math like host counts and netmasks, try the CIDR calculator. To convert numeric permission bits between bases, use the number base converter. For testing permission patterns in path strings, see the regex tester.
Frequently asked questions
What are Unix file permissions?
Unix file permissions control who can read, write, or execute a file. Permissions are set for three categories of users: the file owner, the owner's group, and all other users.
What does chmod 755 mean?
chmod 755 gives the owner read (4), write (2), and execute (1) permissions, totalling 7. The group and others get read (4) and execute (1), totalling 5 each. In symbolic form: rwxr-xr-x.
What is the difference between 644 and 755?
644 (rw-r--r--) is typical for files, the owner can read and write, others can only read. 755 (rwxr-xr-x) is typical for directories and executables, the owner can read, write, and execute; others can read and execute.
What do the read, write, and execute bits mean for directories?
For directories: read (r) allows listing contents, write (w) allows creating or deleting files inside, and execute (x) allows entering the directory (cd). Execute is required for any access to a directory's contents.
What are setuid, setgid, and sticky bit?
These are special permission bits. Setuid (4000) runs an executable with the file owner's permissions. Setgid (2000) runs with the group's permissions. The sticky bit (1000) on a directory prevents users from deleting files they don't own.