Chmod Calculator

Work out Linux and macOS file permissions: tick read, write and execute for owner, group and others to get the octal number (755) and symbolic form (rwxr-xr-x), or type either one to see what it means. Includes setuid, setgid and sticky bits and the chmod command.

This tool runs entirely in your browser.

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How to use the Chmod Calculator

1Tick the permissions you want for owner, group and others — or type an octal or symbolic value.
2Add setuid, setgid or sticky if needed.
3Enter the file name and copy the chmod command.

What is the Chmod Calculator?

Each of the three classes — owner, group, others — gets three permission bits: read (4), write (2) and execute (1). Adding them gives one octal digit per class, so rwx = 7, r-x = 5 and r-- = 4, and rwxr-xr-x is 755. On a folder, execute means “may enter the folder” and read means “may list its contents”.

An optional leading digit sets the special bits: 4 setuid (run as the file’s owner), 2 setgid (run as the group, or new files in a folder inherit its group) and 1 sticky (in a shared folder like /tmp, only owners can delete their files). In the symbolic form they appear as s or t in place of x — uppercase S or T if the underlying execute bit is off.

Frequently asked questions

What is the difference between 644 and 755?

644 (rw-r--r--) lets the owner edit and everyone read — right for normal files. 755 (rwxr-xr-x) also lets everyone execute or enter — right for scripts, programs and folders.

Is chmod 777 safe?

Rarely. It lets every user on the system change or replace the file. Use the narrowest permissions that work, such as 755 or 775 with the right group.

Is the Chmod Calculator free and private?

Yes. The Chmod Calculator is free, needs no account, and runs entirely in your browser. What you type is never sent to a server or stored.

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