What does chmod 755 mean?

Owner: read/write/execute (7). Group: read/execute (5). Others: read/execute (5). Common for executable scripts and web directories.

What does chmod 644 mean?

Owner: read/write (6). Group: read-only (4). Others: read-only (4). Common for non-executable files like HTML, CSS, or config files.

How are the numeric values calculated?

Each permission bit is a power of 2: read = 4, write = 2, execute = 1. Add them for each role. For example, read+write = 6, read+execute = 5, all three = 7.

Does this support special bits (setuid, setgid, sticky)?

No. This tool covers the standard three-digit form. Special bits (4000, 2000, 1000) are rarely needed and have security implications — use the command line for those.

Chmod Calculator

Developer Tools· 30 tools

Free chmod permission calculator. Toggle read/write/execute for owner, group, and others to get the matching numeric (e.g., 755) and symbolic (rwxr-xr-x) chmod values, plus the exact chmod command. Useful for Linux/macOS sysadmins, CI scripts, and web developers setting correct file permissions.

Frequently Asked Questions

References

chmod — Linux manual page — Linux Kernel Archives

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Role	Read	Write	Execute	Value
owner				7
group				5
others				5

Frequently Asked Questions

References and sources

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