About the Circle Area Calculator
Find the area of a circular plot, patio or table from its radius or diameter, in any unit of length.
Also known as: area of circle, circular area, round area calculator.
How to use this calculator
- Enter measure, length.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Open “Step-by-step” to see how the answer was worked out.
- Use Copy result or Share to save the answer or send a link with your inputs.
Circle Area formula
A = π r² = π d² / 4
Worked example
Using the values pre-filled in the calculator above:
- Measure: Diameter
- Length = 12
the calculator returns:
- Area: 113.097336 sq units
- Circumference: 37.699112
Working
A = π × 6² = 113.097336