Free Chmod Calculator
Build Unix file permissions and octal codes.
What is the Chmod Calculator?
On Linux and macOS, every file carries permissions for three groups — owner, group and others — each able to read, write or execute. The `chmod` command sets them with a three-digit octal code like 755, and remembering which number means what is a constant small friction.
This calculator lets you toggle the permissions you want and gives you both the octal code and the symbolic string, right in your browser.
Last updated: Aug 12, 2026
What does this tool do?
You check read, write and execute for the owner, group and others, and the tool builds the matching octal number and the rwx-style symbolic notation.
It works the way you actually think about permissions — pick what each role can do — instead of making you compute the digits yourself.
Key features
Octal and symbolic
Get both 755 and rwxr-xr-x.
Per-role toggles
Set owner, group and others independently.
Live
The code updates as you toggle.
Copy-ready
Grab the code for your chmod command.
Private
Everything runs in your browser.
Example
Common use cases
- Developers — Set the right permissions on scripts and files.
- Sysadmins — Configure file and directory access.
- DevOps engineers — Get permissions right in deploy scripts.
- Students — Learn how Unix permissions work.
- Web developers — Fix file permissions on a server.
- Linux beginners — Understand chmod without memorizing codes.
- Support engineers — Advise on permission fixes.
- Anyone using chmod — Build the number visually.
Benefits
- It removes the mental math of permission digits.
- It shows both octal and symbolic forms.
- It matches how you think about access.
- Nothing you toggle leaves your device.
Tips
- Read is 4, write is 2, execute is 1 — add them per role.
- 755 is common for scripts and directories; 644 for regular files.
- Execute on a directory means you can enter it.
- Avoid 777 — it lets everyone write, which is a security risk.
- The three digits are owner, group, others, in that order.
- Use symbolic notation to read what a code means at a glance.
- Apply with chmod, e.g. chmod 644 file.txt.
- Directories usually need execute to be usable.
Common mistakes to avoid
Using 777 for convenience
Fix: It grants everyone full access — use the least permission needed instead.
Forgetting execute on directories
Fix: Directories need the execute bit to be entered.
Mixing up the digit order
Fix: The order is always owner, group, others.
Confusing read and execute
Fix: Read (4) lets you view; execute (1) lets you run or enter — they're different bits.
How it works
- 1
Toggle permissions
Set read, write and execute per role.
- 2
Copy the code
Use the octal or symbolic result.
Frequently asked questions
Owner can read, write and execute (7); group and others can read and execute (5). The tool shows this as you toggle.
Yes — it gives both the octal code and the rwx symbolic string.
Owner can read, write and execute (7); group and others can read and execute (5). The tool shows this as you toggle.
Yes — it gives both the octal code and the rwx symbolic string.
Read is 4, write is 2, execute is 1; add them for each role to get its digit.
It lets everyone read, write and execute, which is a common security risk. Grant only what's needed.
Owner, then group, then others.
No. Everything runs in your browser.
Conclusion
A chmod calculator turns permission-setting into a visual toggle instead of mental arithmetic. Pair it with the other developer tools when you're working on a server.