CHMOD Calculator

What do file permissions mean?

Unix files have three permission types — read (r), write (w) and execute (x) — for three groups: the owner, the group and everyone else. Each combination creates a three-digit mode.

How is the number calculated?

Each set of rwx permissions is a value from 0 to 7. Read is worth 4, write 2 and execute 1. For example read and write gives 6, and all three gives 7.

What do common modes mean?

• chmod 755 — owner can read, write and execute; others can read and execute.
• chmod 644 — owner can read and write; others can only read.
• chmod 600 — only the owner can read and write.

What is the symbolic form?

Alongside the number, the symbolic notation like rwxr-xr-x describes the same permissions as ten characters: one for the type and nine for the three groups.

How do I use the calculator?

Tick the boxes for each permission and group, or press a preset button like 755 or 644. The numeric value updates live and can be copied in one click.