Developer tools
chmod calculator
Toggle the read, write, and execute bits for the owner, group, and others, and read off the octal value and the ls -l symbolic string. Type an octal value and the checkboxes follow. Everything runs in your browser - nothing is uploaded.
| Permission class | Read | Write | Execute |
|---|---|---|---|
| Owner | |||
| Group | |||
| Others |
How it works
Work out a Unix permission value without memorising the numbers. Tick the read, write, and execute boxes for the owner, the group, and everyone else, and the tool shows you the matching octal value (like 755) and the symbolic string that ls -l prints (like rwxr-xr-x). Type an octal number instead and the checkboxes and the symbolic string update to match, so you can go in whichever direction you need.
Each of the three permission groups maps to one octal digit, built by adding read (4), write (2), and execute (1), which is why 7 is full access and 5 is read plus execute. A plain-English summary spells out who can do what, and the ready-to-copy chmod command saves you typing. Everything runs in your browser, so nothing is sent anywhere.
Example. Tick read, write, and execute for the owner and just read and execute for group and others, and you get 755 with the symbolic form rwxr-xr-x - the usual permissions for a script or a directory. Type 644 and the boxes change to read and write for the owner and read-only for everyone else, the typical setting for a normal file.
FAQ
How do the chmod octal numbers work?
Each digit covers one group - owner, group, then others - and is the sum of read (4), write (2), and execute (1). So 7 is 4+2+1, full access; 6 is read and write; 5 is read and execute; 4 is read only. The three digits together, like 755, set the permissions for all three groups at once.
What does a permission string like rwxr-xr-x mean?
It is the form ls -l prints. It reads in three blocks of three: the owner (rwx = read, write, execute), the group (r-x = read and execute), and others (r-x). A letter means the permission is granted and a dash means it is not. So rwxr-xr-x is the symbolic equivalent of octal 755.
What is the difference between owner, group, and others?
Owner is the user who owns the file, group is the file's assigned user group, and others is everyone else on the system. Each gets its own read, write, and execute permissions, which is why a permission value has three parts. A common setup is full control for the owner and read-only access for the group and others.
Is anything sent to a server?
No. The conversion between checkboxes, octal, and the symbolic string is simple logic that runs entirely in your browser. Nothing you enter is uploaded, logged, or stored, and the tool works offline once the page has loaded.