Chmod Calculator

Linux and Unix-like systems control access to every file and directory with a permission set: what the owner can do, what the owning group can do, and what everyone else can do. Each of those three groups can independently be granted read, write, and execute access, and the whole set is usually written as a three-digit octal code like 755 or 644 — or as a ten-character symbolic string like -rwxr-xr-x, the same format shown by ls -l. Converting between "what I want to allow" and "what number do I type" is the exact conversion this tool automates.

Toggle read, write, and execute independently for the owner, group, and others using the checkbox grid, and the octal code, full symbolic notation, and a ready-to-run chmod command update instantly — nothing to calculate by hand, no need to remember that read is 4, write is 2, and execute is 1. The three less-common special permission bits — setuid, setgid, and the sticky bit — are also supported, each with a plain-English explanation of what it actually does, since they change how the execute bit is displayed (an s or t instead of x) and are easy to get backwards from memory.

Already have a permission code and just need to understand it? Paste an octal value like 750 or a symbolic string like rwxr-x--- into the decode box and the checkboxes update to match, so you can read off exactly what access that code grants before running it against a real file. A row of common presets (755, 644, 700, 600, 777, and more) covers the permission sets used most often for scripts, config files, private keys, and shared directories.

Every calculation happens with plain JavaScript directly in your browser. No file is uploaded, no path or filename you type is transmitted anywhere, and the tool works identically offline — it's a calculator, not a file management service.