What is the difference between this and a regular chmod calculator?

This tool has a dedicated editable field for symbolic notation, not just as an output, and it converts the setuid, setgid, and sticky special bits (the fourth octal digit), which many chmod calculators skip.

What do s, S, t, and T mean in symbolic notation?

A lowercase s in the owner execute position means setuid plus execute; an uppercase S means setuid without execute. The same applies to the group execute position for setgid. A lowercase t in the other execute position means the sticky bit plus execute; uppercase T means sticky without execute.

Can I paste the full ls -l output line?

Paste just the 10-character permission string, such as -rwxr-xr-x or drwxr-xr-x. The tool strips the leading file-type character automatically and converts the remaining 9 characters.

What does a 4-digit octal number like 4755 mean?

The leading digit sets special bits: 4 is setuid, 2 is setgid, 1 is sticky, and they can be summed. The remaining three digits are the normal owner, group, other permissions, so 4755 means setuid plus rwxr-xr-x.

Why does my octal input only show 3 digits?

The leading special-bit digit is omitted whenever it is zero, since chmod 755 and chmod 0755 behave identically. Set any special bit checkbox to see the 4-digit form.

Does this tool change permissions on my server?

No. Everything runs in your browser. Copy the generated chmod command and run it yourself over SSH or in your deployment script.

Chmod Symbolic Converter

Name: Chmod Symbolic Converter
Availability: InStock
Author: Nham Vu

Type an octal number or a symbolic string like rwxr-xr-x in either box and both update instantly, special bits included.

Symbolic notation

Accepts the 9-character form or the 10-character ls -l form with a leading file-type character.

Octal notation

3 digits for owner/group/other, or 4 digits with a leading setuid/setgid/sticky digit.

Permission checkboxes

	Read	Write	Execute	Special

Result

Octal

000

Symbolic

----------

Command

chmod 000 filename

Summary

Type an octal number or a symbolic string like rwxr-xr-x in either box and both update instantly, special bits included.

How it works

Type a symbolic string like rwxr-xr-x into the symbolic field, including a leading file-type character copied from ls -l output such as -rwxr-xr-x.
Or type an octal number like 755 into the octal field, or 4755 to include a special bit.
Both fields, the checkbox grid, and the chmod command update to match whichever one you last edited.
Toggle the read, write, execute checkboxes, or the setuid, setgid, sticky checkboxes, for the same live update.
Click "Copy command" to copy the full chmod command for the current permission set.

Use cases

Convert a symbolic string copied from ls -l output into the octal number needed for a chmod command.
Work out what a four-digit octal mode with a leading special-bit digit actually grants.
Set the setgid bit on a shared directory so new files inherit the group.
Set the sticky bit on a shared writable directory like /tmp so only file owners can delete their own files.
Check a deployment script that sets permissions with a symbolic string before running it.
Teach how setuid, setgid, and sticky bits appear as s, S, t, or T in the execute position.

Frequently Asked Questions

Last updated: 2026-07-22 · Reviewed by Nham Vu