About chmod permissions
This chmod calculator converts Unix file permissions between the tick-box, octal (like 755) and symbolic (like rwxr-xr-x) forms, and gives you the ready-to-run chmod command. Set read, write and execute for the owner, group and others, or type an octal value to go the other way.
How Chmod Calculator works
How to use it
- Tick read, write and execute for owner, group and others.
- Or type an octal value such as 644 or 755.
- Copy the octal, symbolic notation or the chmod command.
How the numbers work
Each permission has a value: read = 4, write = 2, execute = 1. Add them per group, so rwx = 7, rw- = 6, r-x = 5, r-- = 4. The three digits are owner, group and others — for example 755 means rwxr-xr-x.
Common values
644 files (owner read/write, others read), 755 folders and scripts, 600 private files, 777 everything (rarely safe).
Common uses
- Work out a chmod octal value
- Convert octal to rwx notation
- Get the chmod command to run
- Set permissions for a script
- Understand 755 or 644
- Fix file permission errors
- Learn Unix permissions
- Set safe file modes
Frequently asked questions
What does chmod 755 mean?
Owner can read/write/execute; group and others can read and execute (rwxr-xr-x).
How is the octal calculated?
Read=4, write=2, execute=1, added per group of owner, group and others.
What permissions should a file have?
Usually 644 for files and 755 for folders and scripts.
What is 777?
Full permissions for everyone — convenient but usually insecure.
What is symbolic notation?
The rwx form, e.g. rwxr-xr-x, shown alongside the octal.
Does it run chmod?
No — it shows the command for you to run in a terminal.
What is 600?
Owner read/write only — good for private keys and configs.
Is it free?
Yes — completely free with no sign-up.