Linux chmod permission calculator
Translate Linux file permissions between checkboxes, octal modes and symbolic notation. Understand owner, group and other access.
Ordinary permission bits
Change an input to update the result.
Other users can write. Consider the intended access before using this mode.
Inputs are processed in this tab. No text, paths or results are sent to our server or saved in an account. Privacy details.
From input to a useful answer.
- 01
Choose whether the target is a file or directory.
- 02
Enter three octal permission digits and inspect each group.
- 03
Review the generated example before using a command yourself.
Read the three permission groups
The digits describe the owner, the file’s group and everyone else, in that order. Within each digit, read contributes 4, write 2 and execute 1. Add the permissions needed for that group. A value of 6 is read plus write; 5 is read plus execute.
For a regular file, 644 means owner read/write and read-only access for group and others. The leading dash in the symbolic display identifies a regular file; it is not another permission digit. An optional leading zero is accepted, but the calculator displays three ordinary digits.
Directory permissions answer different questions
For a directory, read concerns listing names, write concerns changing directory entries and execute concerns traversing the directory. Useful access often needs combinations: a write bit alone does not promise that someone can create or remove an entry without the required search access.
Select directory mode for those descriptions. For example, 750 gives the owner all three ordinary permissions, the group list/traverse access and others none. Compare that with the access people actually need.
Use the command as a planning example
The site generates a command using an example filename or folder; it never runs chmod or reads your filesystem. Replace the placeholder deliberately if you later use a terminal. There is no recursive option or ownership change.
The display models nine ordinary permission bits. Special bits, access-control lists, mount restrictions and other access rules are outside it. Existing special directory bits may need separate handling by the actual chmod implementation. The world-writable indicator identifies an others-write bit, not a complete permissions audit.
References
GNU Coreutils — Numeric modes ↗Ubuntu 24.04 manpage — GNU chmod ↗A few useful answers
Can I calculate setuid, setgid or the sticky bit?
No. This tool models ordinary owner/group/other permissions only. Inputs such as 4755 or 1777 are outside its scope; an optional zero prefix is accepted.
Does an execute bit guarantee a program will run?
No. It grants an ordinary permission bit. The file’s contents, interpreter, directory access and system restrictions can still affect execution.
Why does directory mode add a d?
The d identifies a directory in the symbolic display. It is not part of the numeric chmod mode.