chmod Calculator — Convert Unix Permissions Between Numeric and Symbolic
Click checkboxes to build 755, 644, 600 and any permission — instantly
Every Linux and macOS developer eventually needs to decode a permission string like rwxr-x--- or construct one from scratch. The chmod calculator makes both directions effortless. The interactive 3x3 grid lets you click read, write, and execute checkboxes for owner, group, and other — the octal code and symbolic string update in real time. Working in reverse? Type any 3-digit octal number directly and the checkboxes flip to match. Preset buttons for the most common configurations (755 for directories, 644 for web files, 600 for SSH private keys) let you jump straight to a known-good starting point. A ready-to-copy chmod command is always one click away.
How to Calculate chmod Permissions
Toggle checkboxes or type an octal number to get any Unix permission in seconds.
Use the checkbox grid
The 3x3 grid has one row each for Owner, Group, and Other and one column each for Read (r=4), Write (w=2), and Execute (x=1). Check the boxes for the permissions you want to grant. The numeric code (e.g. 755) and symbolic string (e.g. rwxr-xr-x) update instantly with every click.
Or type a known octal code
If you already know the number but want to understand which permissions it grants, type the 3-digit octal code directly into the numeric input. The checkboxes update immediately to show the meaning of each digit.
Use a preset and fine-tune
Click one of the preset buttons to jump to a common configuration: 777 (full access), 755 (standard directories), 644 (standard files), 664 (group-writable files), or 600 (private files such as SSH keys). Then check or uncheck individual boxes to fine-tune the permissions before copying the chmod command.
Features
Interactive 3x3 checkbox grid — owner, group, other vs read, write, execute
Live numeric (755) and symbolic (rwxr-xr-x) output on every click
Reverse mode — type any octal number to update checkboxes
One-click preset buttons: 777, 755, 644, 664, 600
Ready-to-copy chmod command with the correct octal argument
Per-entity octal sub-values shown inline
No account or installation required
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Frequently Asked Questions
What does chmod 755 mean?
The three digits map to owner (7), group (5), and other (5). 7 = read+write+execute (4+2+1). 5 = read+execute (4+1). So chmod 755 gives the owner full access and gives group and others read and execute permissions. This is the standard permission for directories and scripts that should be publicly accessible but not publicly writable.
What chmod permissions should I use for website files?
For HTML, CSS, and PHP files use 644 (owner can read/write, group and others can only read). For directories use 755 (owner can read/write/enter, group and others can read/enter). For configuration files with passwords use 600 or 640. Never use 777 in a production environment.
What is the execute permission on a directory?
For directories, the execute bit controls whether a user can enter (cd into) the directory and access files inside it. Without the execute bit on a directory, a user cannot list or access its contents even if the read bit is set.
What is the difference between 664 and 644?
In 664, the group has write permission in addition to read; in 644, the group can only read. Use 664 when multiple users in the same group need to edit the same files, for example in a shared deployment or collaborative project.
Can I use chmod -R to set permissions recursively?
Yes. chmod -R 755 /path sets the given permission on the directory and all of its contents. Be careful when applying execute permission recursively to files — ordinary data files should not be executable. A common pattern is to use find to set directories to 755 and files to 644 separately.