Chmod Calculator Online
Chmod Calculator - Build Linux chmod permissions visually - read/write/execute for owner, group, public, plus setuid, setgid, sticky. Free, client-side.
Build Unix file permissions visually with checkboxes — or paste an octal like 4755 and decode it into a checkbox grid and an ls -l symbolic string.
Permissions matrix
| Identity | Read (r) |
Write (w) |
Execute (x) |
|---|---|---|---|
Owner (u) |
|||
Group (g) |
|||
Other (o) |
Special bits
Quick presets
Generated notation
chmod 000 file.txt
How to Use Chmod Calculator Online
- Tick the permissions matrix - owner, group, and other each get a read, write, and execute column. Every change rebuilds the octal and symbolic outputs instantly.
- Add special bits if needed: setuid, setgid, or the sticky bit. These become the leading digit of the octal (4000, 2000, 1000 respectively).
- Pick a file type - regular file, directory, symlink, device, pipe, or socket. This only changes the first character of the symbolic string (
-rwxr-xr-xvsdrwxr-xr-x). - Edit the filename used in the generated command. The tool quotes it automatically if it contains whitespace or shell-special characters.
- Reverse-decode any octal: type
755or4755into the octal field and the checkboxes light up to match. Handy when a tutorial says "runchmod 2770" and you want to know exactly what that grants. - Pick a preset - 644, 755, 600, 700, 777, 4755 (setuid), 1777 (sticky /tmp) - to jump to a common configuration in one click.
- Press
Ctrl+Enter(⌘+Enteron Mac) or the Copy button to send the fullchmodcommand to your clipboard. Download .sh saves an executable snippet with a header comment.
Frequently asked questions
What does chmod 777 mean?
Three sevens mean “read + write + execute” for owner, group, and everyone. It is the most permissive chmod value and is almost never appropriate in production – it lets any local user modify or replace the file.
What are the standard permissions for web files?
Regular HTML/PHP/text files usually sit at 644 (owner read+write, everyone else read-only). Directories usually sit at 755 (owner full, everyone else read+traverse). Private config files live at 600 or 640.
How does symbolic notation work?
Ten characters: one for file type (-, d, l, b, c, p, s), then three triplets of r/w/x for owner, group, and other. A dash means permission denied; a letter means granted.
What are setuid, setgid, and sticky bits?
Special bits that modify how a file executes or how a directory behaves. Setuid runs the program as its owner (used by tools like sudo as 4755). Setgid makes new files inherit the directory’s group. The sticky bit, most famous on /tmp (1777), lets users only delete their own files.
What’s the difference between 755 and 775?
755 gives the owner full access and everyone else read + execute. 775 also gives the group full access – useful when multiple developers on the same group need write access without opening the file up to the wider world.
Why is my octal sometimes three digits and sometimes four?
When no special bits are set, the octal is three digits (644). When any of setuid, setgid, or sticky is on, the octal gains a leading digit (4755, 2770, 1777). The tool drops the leading zero automatically when none of the special bits apply.
What does an uppercase S or T mean in the symbolic output?
Setuid or setgid without the matching execute bit shows as uppercase S – the special bit is set but not effective. Sticky without execute on other shows as uppercase T. Useful for spotting misconfigured permissions.
Can I paste any chmod value and decode it?
Yes. Paste a 3- or 4-digit octal (each digit 0-7) into the octal box. Invalid characters are stripped automatically; the error block appears only when the result is still not a valid permission value.
Is my input sent to a server?
No. Every computation is a few bitwise operations in your browser. There are no fetch, XHR, or analytics calls on your permissions or filenames.
Does it work offline?
After the page loads, yes. HTML, CSS, and JS are self-contained – disconnect Wi-Fi and keep calculating.