Unix Permissions Calculator — chmod Numeric ↔ Symbolic in Your Browser

chmod Made Visual

I built a Unix Permissions Calculator for devnestio — convert between chmod octal and symbolic notation with a click.

🔗 Try it → unix-perm-calc.pages.dev

Features

• Octal → Symbolic: Type 755 → get rwxr-xr-x
• Symbolic → Octal: Type rw-r--r-- → get 644
• Click-to-toggle bits: Click r/w/x buttons for owner, group, other
• Shows chmod command, ls -l format, binary representation
• Common presets: 777, 755, 644, 600, 700, 664, 444, 000

Unix permission bits at a glance

Permission  Octal  Binary
r (read)      4     100
w (write)     2     010
x (execute)   1     001

So 755 = 111 101 101 → rwxr-xr-x:

• Owner: 7 = rwx
• Group: 5 = r-x
• Other: 5 = r-x

Common permission patterns

Octal	Symbolic	Use case
755	rwxr-xr-x	Executables, directories
644	rw-r--r--	Regular files
600	rw-------	SSH keys, secrets
700	rwx------	Private directories
777	rwxrwxrwx	(avoid — insecure)

Built with

• Pure Vanilla JS, zero dependencies
• Single HTML file deployed on Cloudflare Pages
• Works offline

Part of devnestio — free developer micro-tools.