Chmod Calculator
Build Unix file permissions and get the octal and symbolic chmod values.
Unix file permissions trip up even experienced developers: is it 644 or 755 that a web file needs? Does 777 open a security hole? The permission model — read, write and execute bits for owner, group and others — is simple once you see it laid out, but translating between the checkbox mental model and the octal number you pass to chmod is where mistakes happen.
Toggle the read/write/execute boxes for owner, group and others and this calculator shows the octal value (like 755) and the symbolic notation (rwxr-xr-x) live — or type an octal value to see which boxes it sets. It's the fastest way to get a chmod command right the first time.
How to use Chmod Calculator
- 1
Toggle the permission boxes
Read, write, execute for owner, group and others.
- 2
Or type an octal value
Like 755 — the boxes update to match.
- 3
Copy the chmod command
Use the octal or symbolic value.
Features
- Live octal ↔ checkbox ↔ symbolic conversion
- Ready-to-run chmod command
- Explains common permission sets
Frequently asked questions
Common mistakes to avoid
- Using 777 to 'fix' a permission problem, exposing files to modification by anyone.
- Setting 644 (no execute) on a directory, which prevents entering it — directories need the execute bit.
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