Chmod Calculator
Calculate Unix file permissions interactively. Free, no signup.
How It Works
Toggle the read, write, and execute checkboxes for owner, group, and others. The numeric (e.g. 755) and symbolic (e.g. rwxr-xr-x) notations update instantly. You can also type a numeric value directly. Everything runs in your browser — nothing is sent to a server.
Common Permission Values
| Numeric | Symbolic | Typical use |
|---|---|---|
| 777 | rwxrwxrwx | Everyone can read, write, and execute (rarely safe) |
| 755 | rwxr-xr-x | Directories and executable scripts |
| 700 | rwx------ | Owner-only access, private folders |
| 644 | rw-r--r-- | Regular files, readable by all |
| 640 | rw-r----- | Owner writes, group reads, others none |
| 600 | rw------- | Private files such as SSH keys |
Reading the Numbers
Each permission has a value: read is 4, write is 2, and execute is 1. Add the values you want for a role to get its digit. For example, read plus write is 6, and read plus execute is 5. The three digits, in order, represent the owner, the group, and everyone else.
Frequently Asked Questions
How do I use the chmod calculator?
Tick the read, write, and execute boxes for owner, group, and others. The numeric value (such as 755), the symbolic string (such as rwxr-xr-x), and the full chmod command update instantly. You can also type a three-digit numeric value and the checkboxes update to match.
What does chmod 755 mean?
755 gives the owner read, write, and execute (7 = 4+2+1) and gives the group and others read and execute only (5 = 4+1). In symbolic form that is rwxr-xr-x, a common setting for directories and executable scripts.
What is the difference between 755 and 644?
755 (rwxr-xr-x) adds execute permission for everyone and is used for directories and programs. 644 (rw-r--r--) gives the owner read and write and everyone else read only, which is typical for regular files that should not be executed.
How is the numeric permission calculated?
Each of the three digits sums read (4), write (2), and execute (1) for owner, group, and others in turn. So rw- is 4+2 = 6, r-x is 4+1 = 5, and rwx is 4+2+1 = 7, giving values from 0 to 7 for each digit.
Does this calculator support setuid, setgid, or the sticky bit?
No. It works with the standard three-digit permissions (000 to 777) for owner, group, and others. The special four-digit modes for setuid, setgid, and the sticky bit are not included.