chmod Permission Calculator

Set file permissions by clicking the checkboxes below. The octal value and chmod command update automatically.

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What is chmod?

chmod (change mode) is a Unix/Linux command used to set the access permissions of files and directories. Permissions are defined for three groups: the file owner (user), the owning group, and all other users. Each group can be granted three types of access: read (r = 4), write (w = 2), and execute (x = 1). The permissions for each group are added together to form a single digit, and the three digits form the octal notation — for example, 755 means the owner has full access (7 = 4+2+1) while group and others have read and execute only (5 = 4+1). Permissions can also be expressed in symbolic notation like rwxr-xr-x.

How to Use the chmod Calculator

1. Check or uncheck read, write, and execute boxes for Owner, Group, and Others.

2. The octal value (e.g. 755), symbolic notation (e.g. rwxr-xr-x), and the full chmod command all update in real time.

3. Optionally enter a filename or path to see the exact command tailored to your file.

4. Alternatively, type a known octal value (e.g. 644, 755, 777) and click Apply to see which checkboxes it corresponds to.

5. Copy the generated chmod command and run it in your terminal.

This chmod calculator works entirely in your browser — no data is sent to any server. Supports both input methods: click checkboxes to build permissions visually, or enter an octal value to decode existing permissions. Useful for web developers configuring server files, sysadmins setting directory permissions, and DevOps engineers writing deployment scripts.

Frequently Asked Questions

What does chmod 755 mean? chmod 755 gives the file owner full permissions (read + write + execute = 7), and gives the group and all other users read and execute permissions (read + execute = 5). This is common for executable scripts and directories.

What does chmod 644 mean? chmod 644 gives the file owner read and write permissions (4+2 = 6) and gives group and others read-only access (4). This is standard for web server files like HTML, CSS, and configuration files.

What is the difference between octal and symbolic notation? Octal notation uses three digits (e.g. 755) where each digit represents the combined permission bits for owner, group, and others. Symbolic notation uses letters (e.g. rwxr-xr-x) showing each individual permission explicitly. Both represent the same permissions.

Should I use chmod 777? Avoid chmod 777 on production systems — it grants full read, write, and execute access to everyone, which is a serious security risk. Use the minimum permissions necessary: typically 644 for files and 755 for directories.

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