Chmod Calculator
Tick read, write and execute for owner, group and others, or type a number like 755 or a string like rwxr-xr-x, and copy the matching chmod command.
Chmod Calculator converts Unix and Linux file permissions between octal numbers (like 755 or 644) and symbolic notation (like rwxr-xr-x). Tick read, write and execute for owner, group and others, add setuid, setgid or the sticky bit, and copy the ready-made chmod command. Runs entirely in your browser — no upload, no signup. Made by FreeToolHub.
Permissions
| Read | Write | Execute | Octal | |
|---|---|---|---|---|
| Owner | 0 | |||
| Group | 0 | |||
| Others | 0 |
Special bits
Optional. They add a fourth digit in front of the other three.
chmod 755 filename
chmod u=rwx,g=rx,o=rx filename
In plain words
Common permissions
How it works
Every file on Linux, macOS and other Unix systems has three sets of rights: for its owner, for its group and for everyone else. Each set can allow read (worth 4), write (worth 2) and execute (worth 1), and adding them up gives one digit from 0 to 7. Tick the boxes, type a number like 640 or a string like rw-r-----, or pick a common setting below; every view updates at once and the chmod command is ready to copy. Nothing you enter leaves your browser.
Frequently Asked Questions
What does chmod 755 mean?
755 gives the owner read, write and execute (7 = 4 + 2 + 1), and gives the group and everyone else read and execute (5 = 4 + 1). In symbolic form it is rwxr-xr-x. It is the usual setting for folders, scripts and programs that others may run but only the owner may change.
What is the difference between 644 and 755?
644 (rw-r--r--) lets the owner read and write while everyone else can only read. It is the normal setting for ordinary files such as web pages, images and config files. 755 adds execute for everyone, which a folder needs so people can open it and a script needs so it can run.
How do I read symbolic permissions like rwxr-xr-x?
The nine characters are three groups of three: owner, group and others. In each group the places are read (r), write (w) and execute (x), and a dash means that right is missing. Each right has a value — read 4, write 2, execute 1 — and the sum of each group gives one octal digit, so rwxr-xr-x is 755.
What do setuid, setgid and the sticky bit do?
They form an optional fourth digit in front. Setuid (4) runs a program with the rights of the file's owner, setgid (2) runs it with the file's group, and on a folder makes new files inherit the folder's group. The sticky bit (1) on a shared folder such as /tmp means only a file's owner can delete or rename it. In ls -l they show as s or t in the execute places; a capital S or T means the execute bit underneath is off.
Why should I avoid chmod 777?
777 lets every user on the system read, change and run the file, so any other account or a compromised web process can rewrite it. It is rarely needed. For web servers, use 644 for files and 755 for folders, and make the web server's user the owner or group of anything it must write to.
Where does chmod work and what does -R do?
chmod changes permissions on Linux, macOS and other Unix-like systems, including WSL on Windows. Add -R to change a folder and everything inside it. Be careful with -R and an execute bit: chmod -R 755 also makes every file inside executable. Only the file's owner or root can change its permissions.