Chmod Calculator

Build Unix chmod octal permissions and symbolic rwx notation from owner, group, and others checkboxes.

935.2K uses Updated · 2026-05-21 Runs locally · zero upload
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How to Use Chmod Calculator

Select read, write, and execute permissions for owner, group, and others. The calculator adds the permission weights for each class and produces the three-digit chmod value, such as 755. It also displays symbolic notation such as rwxr-xr-x so you can compare the numeric and readable forms before applying a command.

Formula & Theory - Chmod Calculator

Unix file permissions use three bit groups. Read has weight 4, write has weight 2, and execute has weight 1. Each class receives the sum of its enabled bits, so rwx is 7, r-x is 5, and r— is 4. The final octal mode is owner digit + group digit + others digit.

digit = read*4 + write*2 + execute*1
mode = ownerDigit groupDigit othersDigit

Use Cases for Chmod Calculator

Use it when preparing chmod commands, checking web server file permissions, documenting deployment defaults, teaching Unix permissions, or translating between 755-style numeric modes and rwx-style symbolic modes.

Frequently asked questions about Chmod Calculator

How do I use Chmod Calculator?

Tick read, write, and execute for owner, group, and others. The tool returns the octal chmod mode and symbolic rwx string.

What formula or rule does Chmod Calculator use?

Each permission digit is read*4 + write*2 + execute*1, calculated separately for owner, group, and others.

Is my data stored?

No. All calculations happen in your browser; nothing is sent to a server.