Math
Circle Area Calculator
Calculate circle measurements using radius, including area and circumference.
Calculator
Results
- Area452.3893 sq units
- Circumference75.3982 units
Formula
Area = πr² and circumference = 2πr
Use this formula with the live inputs above to test scenarios instantly.
Assumptions
- Uses π from JavaScript Math.PI precision.
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How this formula works
Circle formulas come from classical geometry. Area grows with the square of radius, while circumference scales linearly with radius, so each metric responds differently when size changes.
Putting both outputs together is helpful for design and estimation tasks: area for coverage/material planning, circumference for perimeter and boundary calculations.
References & citation
Use these references when documenting assumptions, and copy the block below when citing this calculator.
- Algebraic and Percentage Reasoning
Khan Academy
Covers the same percentage transformation logic used in this page.
- Distance and Area Formulas
Math Is Fun
Summarizes standard geometry formulas such as area and circumference.