Chmod Calculator
Convert Unix file permissions between octal (755) and symbolic (rwxr-xr-x) notation, toggle bits, apply u+x style changes and copy the chmod command.
Mode
Type either notation — the other one updates as you type.
Permissions
Toggle each bit. Special bits add the leading octal digit.
| Class | Read | Write | Execute | Value |
|---|---|---|---|---|
| Owner | 7 | |||
| Group | 5 | |||
| Others | 5 |
Apply a change
Preview a relative chmod expression on the current mode.
Result
755rwxr-xr-x
- Octal
- 755
- Symbolic
- rwxr-xr-x
- Command
- chmod 755 file
- Symbolic command
- chmod u=rwx,g=rx,o=rx file
What this mode allows
- Owner: read, write, execute
- Group: read, execute
- Others: read, execute
Chmod Calculator FAQ
- What does chmod 755 mean?
- Each digit is one class: owner, group, others. 7 = read (4) + write (2) + execute (1), and 5 = read + execute. So 755 (rwxr-xr-x) lets the owner do everything and everyone else read and run the file. It is the usual mode for scripts and directories; 644 (rw-r--r--) is the usual mode for regular files.
- What is the fourth (leading) digit?
- It holds the special bits: 4 = setuid, 2 = setgid, 1 = sticky. 4755 runs a program as its owner, 2775 makes new files in a directory inherit its group and 1777 (used by /tmp) only lets users delete their own files. A 3-digit mode means no special bits.
- What do s, S, t and T mean in rwxr-sr-x?
- They replace the execute position when a special bit is set. Lowercase s or t means the special bit and execute are both set; uppercase S or T means the special bit is set without execute, which usually has no effect and is often a mistake.
- How do relative expressions like u+x or go-w work?
- Pick who (u owner, g group, o others, a all), an operator (+ add, - remove, = set exactly) and the permissions (r, w, x, X, s, t). Separate clauses with commas, e.g. u+x,go-w. X adds execute only to directories or files that someone can already execute. The calculator applies the expression to the current mode so you can see the result before running chmod.
- Can I paste the output of ls -l?
- Yes. The symbolic field accepts both rwxr-xr-x and ls -l strings such as drwxr-xr-x or -rw-r--r--@; the file type letter and trailing @, + or . markers are ignored.
- Is anything sent to a server?
- No. Every conversion runs in your browser, and the file name you type is only used to build the command you copy.