Chmod Calculator
Calculate chmod permission values and convert between numeric mode such as 755 and symbolic mode such as rwxr-xr-x.
Concept
What chmod permissions and 755 mean
chmod changes file and directory permissions on Unix and Linux systems. Numeric modes such as 755 and 644 represent permissions for the owner, group, and others as octal digits.
Each digit is the sum of read 4, write 2, and execute 1. For example, 7 means read, write, and execute; 5 means read and execute; and 4 means read only. So 755 gives the owner read, write, and execute permissions, while group and others can read and execute.
The symbolic mode rwxr-xr-x shows the same permission set as letters. The first three characters are for owner, the middle three for group, and the last three for others. This calculator helps compare numeric and symbolic modes before applying a chmod command.
When is 755 used?
It is common for web directories, where others may need to read and traverse them, and for executable scripts that should not be edited by group or others.
What does 644 mean?
The owner can read and write, while group and others can only read. It is often used for regular static files or non-sensitive configuration files.
What should I check?
Values such as 777 grant write permission to everyone and can be risky. Review the target path and permission set before using chmod -R recursively.
This calculator focuses on the three basic permission digits for owner, group, and others. Review setuid, setgid, and sticky bit behavior separately with your server policy.
Chmod Calculator Chmod permission calculator workspace
How to use
- 1 Enter a numeric permission value or select permission checkboxes.
- 2 Adjust read, write, and execute permissions for owner, group, and others.
- 3 Review and copy the numeric mode, symbolic mode, and chmod command.
Common use cases
- Web server file permission checks
- 755 and 644 permission conversions
- Copy-ready chmod permission values
Frequently asked questions
Can I use numeric mode and checkboxes together?
Yes. Entering an octal permission such as 755 updates the owner, group, and others checkboxes plus the symbolic preview, and changing checkboxes recalculates the numeric value.
Can I copy the calculated permission value?
Yes. The copy button copies the current numeric permission value to the clipboard.
Does it calculate special permission bits?
setuid, setgid, and sticky bits are not shown separately. If you enter a four-digit value, only the last three permission digits are used for conversion.