Chmod Calculator
Convert Unix/Linux file permissions between octal notation (755), symbolic string (rwxr-xr-x), and checkboxes. Generate the ready-to-run chmod command instantly.
Chmod Calculator
Toggle checkboxes or type an octal/symbolic value — all fields update instantly.
| Read (r) | Write (w) | Execute (x) | Octal | |
|---|---|---|---|---|
| Owner (u) | 7 | |||
| Group (g) | 5 | |||
| Others (o) | 5 |
Permission meaning
Owner: read, write, execute · Group: read, execute · Others: read, execute
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Understanding Unix file permissions
Every file and directory on a Unix/Linux system has three permission sets: Owner (the user who owns the file), Group (a named group of users), and Others (everyone else). Each set has three bits: Read (r = 4), Write (w = 2), and Execute (x = 1). The octal digit for each set is the sum of the active bits, so rwx = 7, r-x = 5, r-- = 4.
Common permission values
755 (rwxr-xr-x) is typical for executable files and directories — the owner can read, write, and execute; group and others can read and execute. 644 (rw-r--r--) is standard for regular files — owner can read and write, others can only read. 700 (rwx------) gives full access only to the owner, suitable for private scripts.
How to use
- Toggle the Read, Write, Execute checkboxes for Owner, Group, and Others.
- Or type an octal number (e.g. 755) into the Octal field.
- Or type a symbolic string (e.g. rwxr-xr-x) into the Symbolic field.
- Edit the filename in the command box, then copy the full chmod command.
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Frequently Asked Questions
- What does chmod 777 mean?
- chmod 777 grants read, write, and execute permissions to everyone — the owner, group, and all other users. It is rarely appropriate for production files because it allows anyone on the system to modify or execute the file.
- What is the difference between octal and symbolic notation?
- Octal notation represents the three permission sets as digits (e.g. 755), where each digit is the sum of the active bits: read=4, write=2, execute=1. Symbolic notation spells it out as a 9-character string like rwxr-xr-x, where a dash (-) means the permission is not set.
- Do these permissions apply to Windows?
- No. chmod and octal permissions are a Unix/Linux/macOS concept. Windows uses Access Control Lists (ACLs) managed through icacls or File Properties. The tool is intended for Unix-based systems.
- What does the execute bit mean for a directory?
- For directories, the execute bit means 'search' permission — it allows users to enter the directory and access files within it. A directory without execute permission cannot be traversed, even if read permission is set.