Linux chmod calculator
Convert between numeric (e.g. 755) and symbolic (e.g. rwxr-xr-x) file permissions.
The Linux chmod calculator converts a file permission back and forth between its numeric octal form (like 755) and symbolic form (like rwxr-xr-x), updating one field automatically whenever you edit the other.
How to use
- Type into either field — the numeric field accepts 3 octal digits (0-7), the symbolic field accepts 9 characters of r/w/x/-.
- The other field updates automatically to match.
Common use scenarios
- Translating a symbolic permission you see in a file listing into the numeric form for a chmod command.
- Checking what a specific numeric permission (like 644 or 700) actually grants.
- Double-checking a permission setting before applying it to a sensitive file or directory.
- Learning how Unix file permissions map between the two notations.
✓Content & verification reviewed: 2026-08-27
How we verify Linux chmod calculator
How to confirm the conversion matches what you expect.
Each octal digit maps to one 3-character permission group
The three digits represent owner, group, and other permissions respectively, and each digit (0-7) is the sum of read (4), write (2), and execute (1) — e.g. 7 = rwx, 5 = r-x, 4 = r--.
The symbolic form always has exactly 9 characters
Three groups of three (owner, group, other), each showing r/w/x or - for that permission's absence, in a fixed order — a symbolic string that isn't 9 characters is invalid input.
This doesn't cover the optional 4th digit (setuid/setgid/sticky bit)
Only the standard 3-digit/9-character permission set is supported — special bits need to be added separately if your use case requires them.
Before you rely on the result
- You've confirmed which of the two forms (numeric or symbolic) you started from is the one you trust.
- The converted value matches what you expected for that permission level.
- You're aware this doesn't handle setuid/setgid/sticky bit — add those separately if needed.
- You've double-checked before applying an unusually permissive setting (like 777) to anything sensitive.
Who this is for
- Developers and sysadmins translating between chmod notations.
- Anyone checking what a specific numeric permission actually grants.
- People double-checking a permission setting before applying it.
- Students learning how Unix file permissions work.
Real-world examples
Setting a specific permission
Someone sees a symbolic permission in a file listing and converts it to numeric form to use in a chmod command.
Auditing a permission setting
A sysadmin checks what a numeric permission like 750 actually grants before applying it to a shared directory.
Learning Unix permissions
A student toggles through different numeric values to see how each one maps to the symbolic rwx representation.
Limitations
- Doesn't handle the optional 4th digit for setuid/setgid/sticky bit — only the standard owner/group/other 3-digit or 9-character permission set.
Frequently asked questions
What does each digit in a numeric permission mean?
The three digits are for owner, group, and other, in that order. Each digit is the sum of read (4), write (2), and execute (1) for that group.
Does this handle setuid, setgid, or the sticky bit?
No — only the standard 3-digit/9-character permission set. Those special bits would need to be applied separately.
Why did my symbolic input get rejected?
The symbolic field requires exactly 9 characters made only of r, w, x, and - — check for extra characters or a wrong length.
Is 777 a good default permission?
No — 777 grants full read/write/execute to everyone, which is rarely appropriate. Use the narrowest permission that still lets your intended use work.
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