chmod Calculator

Tick read/write/execute boxes to get the octal (755) and symbolic (rwxr-xr-x) forms plus a ready-to-paste chmod command.

What this tool does

Linux permissions come in two notations: octal (755, 644) and symbolic (rwxr-xr-x). Tick the nine boxes — read, write, execute for owner, group, and others — to get both forms plus a ready-to-paste chmod command. Or type an octal value like 755 to see exactly what each digit grants.

Typical use cases

Setting directory and file permissions during deployment; decoding what the current permissions actually mean when debugging “Permission denied”; making a script executable; tightening permissions on sensitive files (.env should be 600, private keys 400).

Caveats

A few combinations cover most needs: 644 for regular files (owner read/write, others read-only), 755 for directories and executable scripts, 600 for private files (owner only), and never 777 in production — “everyone can do everything” is a classic security incident. On directories, x means “can enter”, not “execute”. chmod -R works recursively, but directories and files usually need different permissions — set them separately.