Chmod Permission Calculator
Octal, symbolic and checkbox — all three in sync.
Chmod Permission Calculator converts between the three ways of writing Unix file permissions: the octal number, the symbolic rwxr-xr-x string, and checkboxes for each of owner, group and other. It covers the setuid, setgid and sticky bits, and warns about dangerous combinations. Everything is worked out in your browser.
Loading Chmod Permission Calculator…
Runs entirely on your device. No file or text you enter here is uploaded. How to verify it.
How to use Chmod Permission Calculator
- Tick the permissions, or type an octal or symbolic value.
- Watch all three representations stay in sync.
- Copy the chmod command.
Questions about Chmod Permission Calculator
What do 755 and 644 mean?
755 is read-write-execute for the owner and read-execute for everyone else — the normal setting for a directory or a script. 644 is read-write for the owner and read-only for others — the normal setting for a regular file.
Why is 777 a bad idea?
It lets any user on the system modify the file, and on a shared host that includes other accounts and any compromised process. It is almost never the real fix for a permission problem; the actual issue is usually ownership.
What is the sticky bit for?
On a directory, it stops users deleting files they do not own even when they can write to the directory. It is why
/tmp is mode 1777 and why anyone can create a file there without being able to delete yours.Does it change permissions on my files?
No. It works out the value and writes the command for you; running it is your job, in your own terminal. Nothing on this page can touch a file system.
Does it cover directories as well as files?
Yes, and the difference matters. On a directory the execute bit means "may enter and traverse", not "may run". A directory that is readable but not executable cannot be opened, which is the usual cause of a puzzling permission denied.
Is Chmod Permission Calculator really free, with no limits?
Yes. There is no account, no daily cap, no file-size tier and no watermark, because there is no server cost to recover. The site is funded by clearly disclosed partner recommendations on the Partners page, never by metering the tools.
Are my files or text uploaded when I use Chmod Permission Calculator?
No. Everything is processed by JavaScript running in your browser, on your device. You can verify it: open your browser's developer tools, switch to the Network tab, and use the tool. You will see no request carrying your data — because there is nowhere for it to go.