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Chmod Calculator

Developer Tools

rwx checkboxes to octal and symbolic notation

Quick Answer

Chmod Calculator: rwx checkboxes to octal and symbolic notation. r = 4, w = 2, x = 1; sum per group → octal digit.

Input mode:
755 ⇄ rwxr-xr-x
u=rwx,g=r-x,o=r-x
Owner (u)rwx
Group (g)r-x
Others (o)r-x
Binary111 101 101

How octal works

  1. 1r=4, w=2, x=1. Each digit = sum of enabled bits. rwx=7, r-x=5, r--=4.
  2. 2For 755: owner=7(rwx), group=5(r-x), others=5(r-x).
  3. 3Command: chmod 755 file or chmod u=rwx g=r-x o=r-x file

Common presets

644Regular file: owner rw, others r
755Executable/dir: owner rwx, others rx
600Private: owner only (e.g. keys)
700Private dir: owner only
666World rw (dangerous)
777World rwx (never in production)
400Read-only: protect from edits
640Owner rw + group r
Security: never use 777 on servers. Web files 644, directories 755, SSH keys 600, .ssh dir 700. Special bits (setuid/setgid/sticky) add a 4th leading digit: 4755, 2755, 1777 (/tmp).

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How to Use

  1. Paste or type content: drop code/text into the Chmod Calculator or fill the parameters.
  2. Choose mode/options: switch format, rules or processing as needed.
  3. Live output: results appear instantly — nothing is submitted, data stays in your browser.
  4. One-click copy: copy the output straight into your development environment.

Key Points

  • Chmod Calculator is a free online developer tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: rwx checkboxes to octal and symbolic notation.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

Unix permissions

r = 4, w = 2, x = 1; sum per group → octal digit
Groups: owner | group | others
Common: 755 dirs/scripts, 644 files, 600 private keys, 700 private dirs; avoid 777

FAQ

How do I use the Chmod Calculator?
Open the page and fill in the input fields — results update automatically. rwx checkboxes to octal and symbolic notation.
Are the results accurate?
Yes. Standard formulas and conversion factors are used and verified.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. Everything runs locally in your browser.

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Source & Updates

Based on RFC 4648, ECMA-262 and related specifications. Last updated: 2025-07

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Maintained and periodically reviewed by the YiJianSuan editorial team — review process in ourEditorial Policy.

Cite this page: YiJianSuan. Chmod Calculator[EB/OL]. https://www.yijiansuan.com/en/c/dev/chmod

Results provided by this tool are for reference only and do not constitute professional advice.