Chmod Calculator
Convert Unix file permissions between checkboxes, octal (755) and symbolic (rwxr-xr-x).
| Who | Read (4) | Write (2) | Execute (1) |
|---|---|---|---|
| Owner (u) | |||
| Group (g) | |||
| Others (o) |
Tick boxes, type an octal value or paste a permission string; everything stays in sync.
- Command
- Symbolic command
- ls -l
How Unix permissions work
Every file and directory on Linux, macOS and other Unix systems has three sets of permissions: for its owner, its group and everyone else. Each set has three bits, read (4), write (2) and execute (1). Adding a set’s bits gives one octal digit, and the three digits together form numbers such as 755 or 644. The symbolic form shows the same bits as letters, exactly as ls -l prints them. An optional leading digit holds the special bits: setuid (4) runs a program as its owner, setgid (2) runs it as its group or makes new files in a directory inherit that group, and sticky (1) lets only a file’s owner delete it from a shared directory. Edit any of the three forms here and the other two follow.
Common values
| Octal | Symbolic | Typical use |
|---|---|---|
644 | rw-r--r-- | Regular files: owner edits, everyone reads. Typical for web pages and config. |
755 | rwxr-xr-x | Directories and scripts: owner has full control, others can enter or run. |
600 | rw------- | Private files such as SSH keys or .env; only the owner can read or write. |
700 | rwx------ | Private directories such as ~/.ssh. |
777 | rwxrwxrwx | Everyone can do everything. Almost always a mistake on a server. |
400 | r-------- | Read-only for the owner, often required for private keys (.pem). |
664 | rw-rw-r-- | Shared project files that a team group edits together. |
1777 | rwxrwxrwt | /tmp style: anyone can create files, only the owner can delete them. |
What each bit means
- Execute on a file means it can run as a program; on a directory it means you can enter it.
- Read on a directory lists its entries; write lets you create, rename or delete them regardless of their own permissions.
- A lowercase s or t in the execute slot means the special bit and execute are both set; uppercase S or T means execute is missing, which is usually a mistake.
- chmod -R applies a mode recursively. Prefer the symbolic form (chmod -R u+rwX,go+rX) for trees so files do not become executable by accident.
Privacy
This page performs no network requests. The file name you type is only used to build the command preview and never leaves your browser.