Chmod Calculator
Turn ticks into chmod numbers and back, with every setting explained.
| Read | Write | Execute | |
|---|---|---|---|
| Owner | |||
| Group | |||
| Others |
How to use the Chmod Calculator
- Tick read, write and execute for the owner, the group and everyone else.
- Or type a number such as 755, or letters such as rwxr-xr-x; everything stays in sync.
- Read the plain-English meaning, and switch between file and folder to see the difference.
- Copy the ready-made chmod command, or check what a umask gives new files.
About this tool
On Linux, macOS and other Unix-like systems, every file and folder has three sets of permissions: one for its owner, one for its group and one for everyone else. Each set can allow reading, writing and executing. Those nine switches are written either as letters, as in rwxr-xr-x, or as three digits where read counts 4, write 2 and execute 1, so 7 means all three and 5 means read and execute.
This calculator converts between the checkboxes, the number and the letters in every direction and explains the result in plain words. It matters whether the target is a file or a folder: execute on a folder means being allowed to enter it, and write means being allowed to add and delete files inside, which surprises many people.
It also covers the three special bits. Setuid and setgid make a program run with its owner's or group's rights, and on a folder setgid makes new files inherit the group. The sticky bit, as on /tmp, stops users deleting each other's files. The umask check shows what permissions new files and folders receive by default.
Frequently asked questions
What does chmod 755 mean?
The owner can read, write and execute (7); the group and everyone else can read and execute (5). It is the usual setting for programs, scripts and web folders.
What does chmod 644 mean?
The owner can read and write (6); everyone else can only read (4). It is the usual setting for ordinary files such as documents and web pages.
Should I ever use 777?
Almost never. It lets every user on the system change or delete the file, which is a common security hole on web servers. Fix the ownership instead.
What is a umask?
A mask that removes permissions from new files and folders. With the common umask 022, new files get 644 and new folders get 755.
Does this change anything on my computer?
No. It only calculates and explains. Run the copied command in a terminal yourself to apply it.