Circle from Diameter Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter the diameter.
- Press Calculate.
How it works
From the diameter: radius = diameter ÷ 2, circumference = π × diameter, area = π × radius².
Worked example
diameter 2 m. radius 1 m, circumference ≈ 6.28 m.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.