chmod Calculator
Toggle permissions to get the numeric and symbolic chmod value, or type a value to see the checkboxes.
| Read | Write | Execute | |
|---|---|---|---|
| Owner | |||
| Group | |||
| Others |
How this works
Each permission group (owner, group, others) has three bits: read (4), write (2), execute (1). Their sum gives one octal digit, e.g. read+write = 6. The full chmod value is three digits, one per group — chmod 644 file means owner can read/write, group and others can only read.
Frequently asked questions
What does the execute bit mean for a directory vs a file?
On a file, execute lets you run it as a program. On a directory, execute lets you enter/traverse it (e.g. cd into it) — read alone lets you list contents but not access files inside.
What's a common safe default for web files?
644 for files (owner read/write, everyone else read-only) and 755 for directories (add execute so they can be traversed) are common conventions — but always match your specific security requirements.