Chmod Calculator
Convert Linux file permissions between numeric (755) and symbolic (rwxr-xr-x) notation, with a plain-English breakdown and the chmod command.
How to use
- 1Enter permissions as a number (644, 0755, 4755) or letters (rwxr-xr-x).
- 2Copy the chmod command or read what each group can do.
How it's calculated
Each digit is the sum of read (4), write (2) and execute (1) for owner, group and others. An optional leading digit sets setuid (4), setgid (2) and sticky (1).
Frequently asked questions
What does chmod 755 mean?
The owner can read, write and execute (7); group and others can read and execute (5). It's the usual setting for programs and directories.
What's the difference between 644 and 600?
644 lets everyone read the file but only the owner write it. 600 hides it from everyone except the owner — use it for private keys and secrets.
Why is chmod 777 dangerous?
Anyone on the system can modify or replace the file. It's almost never the right fix for a permissions error.