Chmod Calculator
Convert between octal and symbolic Unix file permission notation. Type 755 and see rwxr-xr-x, or type rwxr-xr-x and see 755. The tool shows permissions for owner, group, and others separately, with a plain-English description of what each set of permissions means (read + write + execute, etc.).
What it does
- ▸Converts octal notation (755, 644, 600) to symbolic (rwxr-xr-x)
- ▸Converts symbolic notation (rwxr-xr-x) to octal
- ▸Accepts ls -l style input (e.g., -rwxr-xr-x)
- ▸Shows permissions for owner, group, and others separately
- ▸Provides plain-English descriptions (read + write + execute)
- ▸Handles setuid, setgid, and sticky bit (4-digit octal)
Use cases
- ▸Figuring out what chmod command to run for a specific permission set
- ▸Understanding what a permission like 2755 means (setgid + rwxr-xr-x)
- ▸Converting permissions from ls -l output to octal for a script
- ▸Checking that a file has the right permissions before deployment
How it works
Type an octal mode (755) or symbolic mode (rwxr-xr-x) into the input
The tool converts to the other notation instantly
Permissions are broken down by owner, group, and others
Each permission set shows a plain-English description
Frequently asked questions
1What do the numbers in octal mode mean?
Each digit represents permissions for one group: owner, group, others. The digit is the sum of read (4), write (2), and execute (1). So 7 = rwx (4+2+1), 5 = r-x (4+1), 4 = r-- (4).
2What are the special bits (setuid, setgid, sticky)?
A 4-digit octal mode like 2755 has a special bit. The first digit is setuid (4), setgid (2), or sticky (1). Setuid (s) lets a program run as its owner. Setgid (s) on a directory makes new files inherit the directory's group. Sticky (t) on a directory prevents users from deleting others' files.
3Can I paste ls -l output?
Yes. The tool accepts ls -l style output like -rwxr-xr-x. It strips the leading type character (- for files, d for directories) and parses the remaining 9 characters as symbolic permissions.
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