Chmod Calculator
| Read | Write | Execute | |
|---|---|---|---|
| Owner | |||
| Group | |||
| Others |
What is Chmod Calculator
A chmod calculator turns Unix and Linux file permissions between the three ways they are usually written: a checkbox grid, a three-digit octal number like 755, and a symbolic string like rwxr-xr-x. Every file has three permission classes (owner, group, and others), and each class can allow reading, writing, and executing. Tick the boxes for what you want and the calculator shows the matching octal value, the symbolic notation, and the ready-to-run chmod command.
How to use
- Tick the read, write, and execute boxes for owner, group, and others.
- Read the octal value (like 755) and the symbolic string (like rwxr-xr-x) update as you click.
- Or type an octal value into the octal field to fill in the grid automatically.
- Copy the chmod command and paste it into your terminal.
When to use it
Setting up a deploy script and need a private key locked down? Tick read and write for the owner only and you get 600 (rw-------), the standard for an SSH key. Doing the opposite for a public web folder, you tick read and execute for group and others to land on 755. The command line is right there: copy chmod 600 filename and paste it straight into your terminal.
Frequently asked questions
What does chmod 755 mean?
755 gives the owner read, write, and execute (7 = 4+2+1), while the group and others get read and execute only (5 = 4+1). In symbolic form that is rwxr-xr-x. It is the common permission for directories and executable scripts that everyone should be able to run but only the owner should change.
How do octal permission numbers work?
Each digit is the sum of read (4), write (2), and execute (1) for one class. Owner comes first, then group, then others. So 640 means owner has read+write (6), group has read (4), and others have nothing (0), which is rw-r-----.
What is the difference between octal and symbolic notation?
They describe the same permissions two ways. Octal is a compact three-digit number (644), while symbolic spells out each bit as a letter or dash (rw-r--r--). The chmod command accepts both, and this calculator shows them side by side.
What permissions should a normal file have?
A regular file that does not need to run is usually 644 (rw-r--r--): the owner can read and write, everyone else can only read. Scripts and programs that must be executable typically use 755. Private files such as SSH keys use 600.
Does this calculator run chmod on my files?
No. It only computes the numbers and the command. Nothing leaves your browser and no files are touched. Copy the generated chmod command and run it yourself in a terminal on the machine that holds the files.
Can I share this tool with my inputs pre-filled?
Yes. The URL updates automatically as you change the permissions. Copy it from the address bar or use the Share button, and anyone who opens the link will see the same permissions ready to go.
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