# Chmod Calculator

> Free chmod calculator. Pick read/write/execute for user, group and others and get the octal mode, symbolic notation and chmod command instantly.

Unix file permissions without the headache: tick read, write and execute for user, group and others, and get the octal mode, symbolic notation and the exact chmod command.

*Interactive tool: enter your values at https://toollantern.win/chmod-calculator/ and results update instantly in your browser.*

## What the tool does

Every Unix file has nine permission bits: read, write and execute for the owner, the group and everyone else. Tick the boxes and the tool shows the octal number (like 644), the symbolic string (like rw-r--r--), a plain-words description, and the chmod command to apply it.

## Worked example

A typical web file is **644** (rw-r--r--): the owner can read and write, everyone else can only read. A script you run is **755** (rwxr-xr-x): everyone can read and execute, only the owner can write.

## Common modes

644 for files, 755 for directories and scripts, 600 for private files like SSH keys (owner read/write only). Avoid 777: it gives everyone full control and is a security hole.

## Frequently asked questions
### What do the octal numbers mean?

Each digit is one class: user, group, others. Read is 4, write is 2, execute is 1; add them up. So 7 means read+write+execute, 6 means read+write, 4 means read-only.

### What is the difference between 644 and 755?

644 (rw-r--r--) is standard for files: nobody gets execute. 755 (rwxr-xr-x) adds execute for everyone, used for directories (needed to list them) and scripts.

### Why is 777 dangerous?

It grants read, write and execute to literally everyone on the system. Any compromised account or process can then modify or replace the file.

### Does this change my files?

No. The tool only computes the values and shows the command. Run the chmod command yourself on your own machine.

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Interactive version: https://toollantern.win/chmod-calculator/