Convert Linux file permissions between checkboxes, octal (755) and symbolic (rwxr-xr-x) in your browser.
Unix and Linux control access to every file with nine permission bits: read, write and execute, granted separately to the owner of the file, to its group, and to everyone else. The chmod command accepts those bits as a compact octal number — 755, 644 — or as a symbolic string such as rwxr-xr-x, and remembering how one maps to the other is exactly the kind of thing nobody should have to memorize. This calculator keeps the three representations synchronized: change a checkbox, the octal and symbolic values follow; type an octal or symbolic value, the checkboxes follow.
The math is simple once you see it spelled out. Each permission has a fixed value — read is 4, write is 2, execute is 1 — and each octal digit is the sum of the values granted to one class. So 755 means the owner gets 4+2+1 (read, write and execute) while group and others get 4+1 (read and execute). The tool shows that breakdown for every digit, together with the equivalent chmod command in both numeric and u=/g=/o= symbolic form, so you can paste it straight into a terminal.
Typical uses: fixing permissions after uploading files to a web server (644 for files, 755 for directories and scripts is the classic combination), locking a private key or .env file down to 600, or double-checking a value before running chmod over SSH or in a CI pipeline. The 777 preset is included because it is common in tutorials — with a visible warning, since giving every user full write and execute access is rarely a good idea on any machine reachable from the internet. Everything runs 100% in your browser: no command is executed and nothing is sent to any server.
Each permission has a value: read = 4, write = 2, execute = 1. Each octal digit is the sum of the values granted to one class (owner, group, others). Example: rwxr-xr-x = (4+2+1)(4+1)(4+1) = 755.
It gives the owner read, write and execute (7 = 4+2+1) and gives group and others read and execute (5 = 4+1). In symbolic notation that is rwxr-xr-x — the standard permission for directories and executable scripts on web servers.
The execute bit. 644 (rw-r--r--) lets the owner read and write while everyone else only reads — right for ordinary files. 755 adds execute for all classes, which directories need to be entered and scripts need to run.
Usually, yes. 777 lets any user on the system modify and execute the file, so a compromised account or a malicious script can rewrite it. If a program only works with 777, the real problem is almost always file ownership — fix it with chown instead.
A leading fourth digit sets the special bits: setuid (4), setgid (2) and sticky (1). This calculator covers the three classic permission digits; if you paste a four-digit value, the last three digits are used.
No. The conversion is pure JavaScript running on your device — no command is executed, nothing is transmitted and nothing is stored.
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