chmod 640 fileA chmod calculator translates Linux file permissions between the numeric form (like 755) and the symbolic form (like rwxr-xr-x) so you never have to do the mental math. It is a must-have for anyone managing a server, deploying a website, or learning Unix. Our free calculator also outputs the exact chmod command to copy into your terminal.
For owner, group, and others, check Read (4), Write (2), and Execute (1) as needed. The numeric, symbolic, binary, and command fields update live.
Short on time? Click 644, 755, 777, 600, 700, 775, 666, or 400 to apply a common pattern instantly.
The "Linux command" line shows chmod 640 file (or your chosen value). Paste it into your shell to apply the permission.
Each level is a sum: Read=4, Write=2, Execute=1. Owner, group, and other each get one digit. Symbolic notation spells it out as rwx per level. Both mean the same thing — the calculator keeps them in sync so you can read either form. Pair it with the Base64 tool or JSON formatter when preparing config snippets.
Default to the principle of least privilege: give a file only the access it needs. Use 644 for files and 755 for directories, reserve 600/700 for secrets, and avoid 777 in production. If you manage timestamps alongside permissions, the Unix timestamp converter helps when reading logs.
When you upload a site, correct permissions keep it both reachable and safe. After setting them, you can compress assets with the SVG compressor or convert artwork with the PNG to SVG converter.
The calculator runs entirely in your browser. Nothing you type is sent to a server, so permission planning stays local.
chmod is the Unix and Linux command that changes file and directory permissions, controlling who can read, write, and execute them. Our calculator shows the result before you run anything.
Numeric notation uses digits (e.g. 755); symbolic notation uses letters like rwxr-xr-x. They describe the same thing — the calculator converts between them instantly.
Read it in three groups: owner (7 = rwx), group (5 = r-x), others (5 = r-x). So 755 means the owner can do everything, while group and others can read and execute.
644 is a standard file (owner read/write, others read). 755 is a standard directory or executable script (others can also execute). 777 grants full access to everyone and is rarely advisable.
Use 644 for normal files (HTML, images, configs). Use 755 for directories and scripts that need to be run. This is the safe default for most web projects.
Almost never. 777 lets any user read, modify, and execute the file, which is a security risk. Prefer 644 for files and 755 for folders; reach for 777 only in a throwaway sandbox.
Beyond read/write/execute there are special bits: setuid and setgid run a file with the owner's privileges, and the sticky bit (commonly 1777 on /tmp) restricts file deletion. The basic calculator covers the standard rwx triplet.
Run chmod 640 file to set numeric permissions, or chmod u+rw,go=r file for symbolic. The tool prints the exact command for whatever you select.
chmod changes permission (rwx); chown changes ownership (which user or group owns the file). You usually set ownership once and tune permissions with chmod afterward.