This calculator converts Unix file permissions between the familiar checkbox view (read, write, execute for owner, group and others) and the octal chmod number like 755 — instantly and locally, in both directions.
How to use it
- Toggle the read/write/execute boxes for owner, group and others.
- The octal value (e.g. 755) updates live.
- Or type an octal value to see the checkboxes.
- Copy the chmod command.
About Chmod Calculator
Unix permissions trip up even experienced developers. Is 644 right for a file? Should a script be 755 or 777? The octal notation packs three permission bits per role into a single digit, which is compact but unintuitive. This calculator makes the relationship visible: tick the boxes and see the number, or type the number and see what it grants. It also shows the symbolic form (rwxr-xr-x) and a ready chmod command. Everything runs in your browser.
FAQ
What does 755 mean?
Owner can read, write and execute (7); group and others can read and execute but not write (5). Common for scripts and directories.
Why is 777 risky?
It grants everyone full read, write and execute. That is rarely necessary and can be a security risk.
What is the difference between 644 and 755?
644 (no execute) suits regular files; 755 (with execute) suits scripts and directories that need to be entered or run.