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Linux Chmod Permissions Calculator
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This chmod calculator converts Linux file permissions between numeric octal notation (like 755 or 644) and symbolic notation (like rwxr-xr-x), so you never have to mentally add up read/write/execute bits again. It's a everyday utility for sysadmins configuring server file permissions, developers setting up deployment scripts, and anyone learning how Unix permission bits work for owner, group, and others. Instead of calculating that read+write+execute equals 7 and read+execute equals 5 by hand, this linux permissions calculator lets you toggle individual permission checkboxes and instantly see the resulting octal value, or type an octal number and see the symbolic breakdown. It removes the guesswork from a command like chmod 644 file.txt, showing exactly what access each user class gets. Calculation happens instantly in your browser with nothing transmitted anywhere. Toggle permissions or enter an octal value below to see the conversion immediately.
Features
- Converts octal permissions (e.g. 755) to symbolic notation (rwxr-xr-x)
- Converts symbolic notation back to octal instantly
- Interactive checkboxes for owner, group, and others permissions
- Explains what each permission bit grants (read, write, execute)
- Shows the exact chmod command to run
- Instant two-way conversion as you toggle or type
- Covers special bits like setuid, setgid, and sticky bit
Why use this linux chmod permissions calculator?
- Instant conversion with no manual bit-math
- Fully private - runs entirely in your browser
- Accurate permission calculations for owner, group, and others
- Great for both quick lookups and learning permission concepts
- Free with unlimited use
Frequently asked questions
What does chmod 755 mean?
755 grants the owner read, write, and execute permissions (7), while group and others get read and execute only (5), commonly used for executable scripts and directories.
What does chmod 644 mean?
644 grants the owner read and write permissions (6), while group and others get read-only access (4), a common setting for regular files.
How is each octal digit calculated?
Each digit is a sum of read (4), write (2), and execute (1) bits for that user class - for example, read+write+execute equals 4+2+1=7.
What's the difference between symbolic and octal chmod notation?
Symbolic notation (like rwxr-xr-x) spells out permissions letter by letter per user class, while octal notation (like 755) represents the same permissions as three compact digits.
What does the setuid bit do?
The setuid bit causes an executable file to run with the permissions of its owner rather than the user who launched it, commonly represented as an extra leading digit (e.g. 4755).
What permission should I use for a directory that others can browse but not modify?
A common setting is 755, giving the owner full access while others can read and enter (execute) the directory but not write to it.
What does a dash (-) mean in symbolic permission notation?
A dash indicates that permission is not granted for that position - for example, 'r-x' means read and execute are allowed but write is denied.