chmod

CHMOD Calculator

Type an octal mode such as 644 or 4755, a symbolic mode such as rwxr-xr-x, or tick the permissions you want. All three stay in sync, with a breakdown for owner, group and others and a ready-made chmod command.

Back

1. Mode

Two-way conversion
Permission checkboxes
ClassReadWriteExecute
Owner
Group
Others
Special bits

Examples (common notations, not recommendations):

2. Result

Owner · group · others
Enter an octal or symbolic mode, tick permissions or choose an example.
About this tool

About CHMOD Calculator

CHMOD Calculator converts Unix and Linux file permissions between octal notation, such as 755 or 4755, and symbolic notation, such as rwxr-xr-x or rwsr-xr-x. It shows owner, group and others separately, includes setuid, setgid and the sticky bit with correct s, S, t and T display, and gives a chmod command example.

Permission modes are easy to misread, especially with special bits. Seeing octal, symbolic and checkbox views together makes it clear what a mode allows.

How to use

Step by step

  1. Type an octal mode, a symbolic mode or tick the permission boxes.
  2. Optionally set setuid, setgid or the sticky bit.
  3. Read the breakdown for owner, group and others.
  4. Optionally enter a file name for the chmod command.
  5. Copy or download the summary.
Key features

What it offers

  • Octal ↔ symbolic ↔ checkbox conversion
  • setuid, setgid and sticky bit support
  • Correct s, S, t and T display
  • Accepts ls -l style strings with a file-type letter
  • chmod command example with a safely quoted file name
  • Clear errors for invalid digits and characters
Best practices

Tips for best results

  • Give write access only to those who need it.
  • Use setuid and setgid sparingly and deliberately.
  • Remember that directories need execute (x) to be entered.
  • Check the owner and group of a file as well as its mode.
Benefits

Why people use it

Two-way

Octal and symbolic always match.

Complete

Special bits included.

Clear

Plain-language breakdown.

Offline-friendly

Runs in your browser.

FAQ

Common questions

Each digit is the sum of read (4), write (2) and execute (1) for owner, group and others. So 7 = rwx, 5 = r-x, 4 = r-- and 0 = ---. 755 therefore means rwxr-xr-x.
A leading digit sets the special bits: 4 = setuid, 2 = setgid, 1 = sticky. They can be combined, so 6755 sets both setuid and setgid.
In the execute position, s means setuid or setgid with execute also set, and S means the special bit is set but execute is not. For others, t means the sticky bit with execute, and T means sticky without execute.
On a directory, it lets only a file’s owner (or the directory owner or root) delete or rename files in it, even when others can write there — as on /tmp, which is commonly 1777.
No. They are common examples of how modes are written. Whether a mode is appropriate depends on the file, its owner and how it is used, so none is universally safe.
Yes. A 10-character string such as -rwxr-xr-x or drwxr-xr-x is accepted; the first character (the file type) is ignored.
No. It only converts and explains modes. Run the chmod command yourself if you want to apply one.

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Private by design

This runs entirely in your browser

No file or text you enter here is uploaded. Encoding and decoding happen on your device using native browser APIs — close the tab and nothing remains on a server.

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