Chmod Calculator
Work out Unix file permissions in seconds. Tick read, write and execute for the owner, group and others
to get the octal value, the symbolic string and the exact chmod command — or type a value to set the grid.
Everything runs in your browser; nothing is sent anywhere and nothing is stored.
| Read 4 | Write 2 | Execute 1 | |
|---|---|---|---|
| Owner | |||
| Group | |||
| Public (other) |
How to use the chmod calculator
- Tick the boxes for each class of user — Owner, Group and Public (other) — across the Read, Write and Execute columns.
- The octal value, symbolic string and full
chmodcommand update instantly as you tick. - Already have a value? Type it into the reverse box (for example
644orrw-r--r--) and the grid updates to match. - Click Copy to grab the octal value or the whole command.
Each digit is the sum of read = 4, write = 2 and execute = 1. Common values:
755 (rwxr-xr-x) for directories and scripts, 644 (rw-r--r--) for regular files,
700 (rwx------) for private files, and 600 (rw-------) for private data.
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Frequently asked questions
What is a chmod calculator?
A chmod calculator turns Unix file permissions into the numbers and letters that chmod understands. Tick who can read, write and execute a file and it gives you the octal value (like 755), the symbolic string (like rwxr-xr-x) and the ready-to-run chmod command.
How do the octal permission numbers work?
Each permission has a value: read = 4, write = 2 and execute = 1. Add the values for each class of user (owner, group, other) to get one digit. For example read + write + execute is 4+2+1 = 7, while read + execute is 4+0+1 = 5, giving the familiar 755.
What does rwxr-xr-x mean?
That is the symbolic form, read in three groups of three. rwx for the owner means read, write and execute; r-x for the group means read and execute but no write; r-x for others is the same. A dash means that permission is not granted.
What is the difference between 755 and 644?
755 (rwxr-xr-x) is common for directories and executable scripts: the owner can change them, everyone can read and run them. 644 (rw-r--r--) suits ordinary files: the owner can edit, everyone else can only read. Avoid 777 on anything public — it lets anyone write.
Can I convert a permission back to checkboxes?
Yes. Type an octal value such as 755 or 0755, or a symbolic string such as rwxr-xr-x, into the reverse box and the grid, octal, symbolic and command all update to match.
Is my data sent anywhere?
No. Every calculation runs entirely in your browser — nothing is uploaded to a server and nothing is stored.