Chmod Calculator
Calculate Unix and Linux file permissions interactively without octal arithmetic. Toggle read, write, and execute checkboxes for owner, group, and others — see both the numeric chmod value (e.g. 755) and the symbolic notation (e.g. rwxr-xr-x) update in real time.
| Read (4) | Write (2) | Execute (1) | Octal | |
|---|---|---|---|---|
| owner | 7 | |||
| group | 5 | |||
| others | 5 |
How to Use the Chmod Calculator
- 1
Select permissions for Owner
Check Read, Write, and/or Execute for the file owner. Checking all three gives a value of 7.
- 2
Select permissions for Group
Choose the permissions for users in the file's assigned group.
- 3
Select permissions for Others
Choose permissions for all other users on the system.
- 4
Copy the chmod value
The numeric value (like 755) and symbolic notation (like rwxr-xr-x) are shown instantly. Copy the numeric value to use in a chmod command.
Key Features
Numeric + Symbolic
Shows both the numeric chmod value (755) and symbolic notation (rwxr-xr-x) simultaneously.
Toggle UI
Click permissions rather than doing octal arithmetic — eliminates calculation errors.
Instant Updates
Both numeric and symbolic outputs update with every checkbox click.
Pro Tips
Common values to memorise: 755 for web scripts, 644 for static files, 600 for SSH private keys, 700 for private directories.
Never use 777 (world-writable) on production servers — it is a serious security risk that allows any user to modify the file.
For directories, the execute bit means the ability to enter and traverse the directory — it is required for cd to work.
Privacy Note
All processing in this tool runs entirely in your browser — no data is transmitted to any server. Your input is never logged, stored, or shared. This tool is free to use with no account or registration required.
Frequently Asked Questions
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