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Choose permissions
WhoReadWriteExecute
Owner (u)
Group (g)
Others (o)
Result
755
Numeric (3 digits)
0755
With special bits (4 digits)
rwxr-xr-x
Symbolic
chmod 755 file.txt
Command to run

    How 755 differs from 644

    The three digits stand for owner, group and others, in that order. Each digit is read 4 plus write 2 plus execute 1, so 7 is 4+2+1 (read, write and execute), 5 is 4+1 (read and execute) and 4 is read only.

    755 is the usual choice for directories and executables. On a directory the execute bit means "you may enter it", so removing it makes the directory unusable even when it is readable. 644 is the usual choice for regular files: the owner can edit, everyone else can only read. Older guides still suggest 777 for web files, which lets anyone overwrite them; avoid it on shared hosts.

    The three special bits

    The leading digit of the four-digit form holds the special bits. setuid (4) runs the program as its owner and setgid (2) does the same for the group. setgid on a directory makes new files inherit the parent group, which is why shared directories use it. sticky (1) is the 1777 on /tmp: everyone may write, but nobody may delete another user's files.

    An uppercase S or T in the symbolic form means the special bit is set while the execute bit is not. That combination is usually unintended, so this tool shows the case faithfully.

    NumericSymbolicTypical use
    644rw-r--r--Regular files. Only the owner can edit
    755rwxr-xr-xDirectories, executables, shell scripts
    600rw-------SSH private keys, .env and other private config
    664rw-rw-r--Files edited by several people in one group
    1777rwxrwxrwt/tmp. Anyone may write, nobody may delete others' files

    All calculation happens in your browser. Nothing you type is sent to a server.

    Frequently asked questions

    What does chmod 755 mean?

    The owner gets read, write and execute; group and others get read and execute. Each digit is read 4 plus write 2 plus execute 1, so 7 is 4+2+1 and 5 is 4+1. It is the usual mode for directories and executables.

    Should I use 644 or 755?

    Use 644 for regular files and 755 for directories and executables. On a directory the execute bit means permission to enter it, so removing x from a directory makes it unusable.

    Why is the S or T uppercase in the symbolic form?

    Because the special bit is set while the execute bit at that position is not. Lowercase s or t means the execute bit is set as well. Uppercase is usually unintended, so it is worth checking.

    Is anything sent to a server?

    No. The conversion and the command are produced entirely in your browser with JavaScript. Nothing you type leaves the page.