CHMOD Calculator — a convenient tool for setting access permissions. Enter a combination and get the result in both numeric and symbolic format.
| Permissions | Owner PermissionsOwner Permissions | Group PermissionsGroup Permissions | Others PermissionsOthers Permissions |
|---|---|---|---|
ReadRead | |||
WriteWrite | |||
ExecuteExecute |
Convert between octal (numeric) and symbolic permission formats instantly. Enter 755 to see rwxr-xr-x, or vice versa.
See a clear visual representation of permissions with checkboxes showing read, write, and execute permissions for each user type.
Set permissions for owner (user), group, and others separately, with support for all standard permission combinations.
The CHMOD Calculator helps you quickly determine and correctly set file and directory permissions in Unix-like systems (Linux, macOS, BSD). The tool converts permissions between symbolic and numeric (octal) formats, visualizes access rights, and generates ready-to-use terminal commands.
This is especially important for server administration, web application deployment, CI/CD pipelines, containers, and storage systems.
In Unix systems, access to a file is defined for three user groups:
User (u) — the file owner or assigned user.
Group (g) — users who belong to the file’s group.
Others (o) — all other system users.
Each group can have three types of permissions (r, w, x):
Permission | Symbol | Octal | For Files | For Directories |
|---|---|---|---|---|
Read | r | 4 | Read file contents | List directory contents |
Write | w | 2 | Modify file | Create, delete, rename files |
Execute | x | 1 | Run as program/script | Enter directory (cd) and access items inside |
Without the execute (x) permission, a directory is effectively inaccessible — even if read (r) permission is granted.
The sum of values determines the final permission number for each user group.
Access Level | Symbolic | Calculation | Octal |
|---|---|---|---|
Full access | rwx | 4+2+1 | 7 |
Read & write | rw- | 4+2 | 6 |
Read & execute | r-x | 4+1 | 5 |
Read only | r-- | 4 | 4 |
Write & execute | -wx | 2+1 | 3 |
Write only | -w- | 2 | 2 |
Execute only | --x | 1 | 1 |
No access | --- | 0 | 0 |
Use Case | Symbolic | Octal |
|---|---|---|
Full access (NOT recommended) | rwxrwxrwx | 777 |
Shared group directories | rwxrwxr-x | 775 |
Shared group files | rw-rw-r-- | 664 |
Private directories and scripts | rwx------ | 700 |
Private files (SSH keys, passwords) | rw------- | 600 |
Directories & executable scripts | rwxr-xr-x | 755 |
Standard web files (HTML, CSS, images) | rw-r--r-- | 644 |
When running the chmod command, you can control how results are displayed:
Verbose (-v) — detailed output showing changes for each processed file.
Changes (-c) — display only files whose permissions were actually modified.
Silent (-f) — suppress error messages (for example, permission denied or missing files).
Default — standard mode showing only critical messages (such as errors), without details on successful operations.
These settings control how and where permissions are applied:
Recursive (-R) — apply permissions to a directory and all its contents, including subdirectories, files, and symbolic links (behavior may vary by system).
Reference File (--reference=FILE_NAME) — copy permissions from an existing file instead of specifying a numeric mode.
Special Permission Bits:
Setuid (+s for owner). Executable runs with the file owner’s privileges instead of the user who launched it.
Setgid (+g). Behavior depends on object type: for files (executable runs with the file’s group privileges), for directories (newly created files inherit the directory’s group, simplifying team collaboration).
Sticky Bit (+t). Mainly used on shared directories. Allows users to delete or rename only the files they own (commonly used on /tmp).
The CHMOD calculator helps you calculate file and directory permissions for Linux and Unix systems. This tool converts between numeric (octal) and symbolic permission formats, making it easy to set the correct permissions for files and directories.
CHMOD permissions control who can read, write, and execute files or directories. The tool supports both three-digit octal notation (like 755) and symbolic notation (like rwxr-xr-x), providing flexibility for different use cases.
Perfect for system administrators, developers, and anyone working with Linux/Unix systems who needs to understand and set file permissions correctly.
A chmod calculator is a tool that helps you calculate and understand Unix/Linux file permissions. It converts between numeric (octal) permission notation (like 755) and symbolic notation (like rwxr-xr-x), making it easier to set correct file permissions.
The three digits represent permissions for three different user groups: Owner (first digit), Group (second digit), and Others (third digit). Each digit is a sum of read (4), write (2), and execute (1) permissions. For example, 755 means owner has read+write+execute (7), group has read+execute (5), and others have read+execute (5).
Simply enter the numeric permission value (like 755, 644, 777) or use the checkboxes to select individual permissions. The calculator will instantly show you the symbolic notation and explain what each permission means for the file owner, group, and others.
Common values include: 755 (rwxr-xr-x) for executable files, 644 (rw-r--r--) for regular files, 600 (rw-------) for private files, 777 (rwxrwxrwx) for full access, and 750 (rwxr-x---) for files accessible by owner and group only.
No, 777 permissions give read, write, and execute access to everyone, which is a security risk. Only use 777 for temporary files or in very specific controlled environments. For web files, 755 for directories and 644 for files is usually sufficient.
For files: read (r) allows viewing content, write (w) allows modification, execute (x) allows running the file. For directories: read (r) allows listing contents, write (w) allows creating/deleting files, execute (x) allows accessing the directory. A directory needs execute permission to be accessible.
This tool is specifically designed for Unix/Linux chmod permissions. Windows uses a different permission system (ACL - Access Control Lists), so the numeric values and symbolic notation won't directly apply to Windows file permissions.
Use the chmod command in your terminal: 'chmod 755 filename' or 'chmod u+rwx,g+rx,o+rx filename'. The calculator shows you both the numeric and symbolic formats you can use with the chmod command.
