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Calculate Unix file permissions.
Chmod Calculator is a free browser-based tool that helps you calculate unix file permissions. It is part of ToolsMonk's developer tools collection, so you can finish the job without downloading software, creating an account, or jumping between multiple websites.
This tool is especially useful for workflows such as working out the chmod number for a set of permissions, decoding what a permission like 644 or 755 actually means, and setting correct permissions for web files and scripts. Because it runs directly in your browser, you can use it on desktop, tablet, or mobile while keeping the process fast and easy for one-off tasks as well as repeat work.
Chmod Calculator is designed for people who want a practical, privacy-friendly workflow with instant results inside the larger ToolsMonk library.
Toggle read, write, and execute for owner, group, and others
The octal number (e.g. 755) and symbolic notation (rwxr-xr-x) update live
Or enter an octal number to see what it permits
Copy the chmod value for your command
Converts Unix file permissions between symbolic (rwx) and octal (e.g. 755)
Toggle read/write/execute for owner, group, and others
Shows the matching chmod number and symbolic notation
Explains what each permission set allows
Runs in your browser — nothing is uploaded
Free, with no signup
Working out the chmod number for a set of permissions
Decoding what a permission like 644 or 755 actually means
Setting correct permissions for web files and scripts
Learning Unix/Linux file permissions
Chmod Calculator is a powerful free online tool available on ToolsMonk that helps you calculate unix file permissions. Whether you're a professional, student, or casual user, our chmod calculator provides instant, accurate results right in your browser without requiring any software installation or account creation.
As part of our Developer Tools collection, this tool is designed with simplicity and power in mind. All processing happens client-side, ensuring your data remains completely private and secure. The tool works seamlessly across all modern browsers on desktop, tablet, and mobile devices.
Chmod Calculator converts Unix/Linux file permissions between the symbolic form (rwxr-xr-x) and the octal number used with chmod (like 755), with checkboxes for read, write, and execute across owner, group, and others.
The octal system clicks once you see the arithmetic: each of the three digits covers one group — owner, group, others — and is the sum of read (4), write (2), and execute (1). So 7 is all permissions, 5 is read+execute, 6 is read+write, and a number like 755 reads as 'owner everything, group and others read+execute'. The calculator shows both notations live so you can learn by toggling.
Two everyday values dominate: 644 (rw-r--r--) for regular files, where the owner edits and others read, and 755 (rwxr-xr-x) for directories and executables. A subtlety worth knowing is that 'execute' on a directory means the right to enter and traverse it — which is why folders need 755, not 644.
A security note the tool encourages: avoid 777 (full access for everyone) on servers, as it lets anyone modify the file and is rarely truly needed — set the minimum permissions instead. Everything runs in your browser with nothing uploaded. Pair it with the other ToolsMonk developer tools for your sysadmin and web tasks.
Rule of thumb: 644 for files, 755 for directories and scripts
Avoid 777 on web servers — it's a security risk and rarely necessary
Each digit = read(4) + write(2) + execute(1) for owner / group / others
Common questions about this tool, its workflow, and what to expect before you use it.
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