Circle Calculator
Calculate area from radius, or find radius from area
Area of Circle
78.54
Using π = 3.14
Radius
5 cm
📐 Formula
A = πr²
Area = π × radius²
📝 Step-by-Step
💡 Pi Comparison:3.14 is an approximation. 22/7 ≈ 3.142857. π ≈ 3.14159265 is the exact value.
💡 Did you know?The formula for circle area was discovered by ancient Greek mathematicians over 2,000 years ago!
What is a Circle Area Calculator?
A circle area calculator is a tool that helps you find the area of a circle quickly and accurately. Whether you're a student learning geometry, a teacher preparing lessons, or a professional needing quick calculations, this tool makes it easy.
Formula
A = π × r²
Where A = Area, π = Pi (3.14159), r = Radius
Example
Example: Find the area of a circle with radius 5 cm
A = π × r²
A = 3.14159 × 5²
A = 3.14159 × 25
A = 78.54 cm²
Common Uses
- ▸Geometry Homework: Students use circle area formulas in math class
- ▸Construction: Calculating circular spaces, columns, or foundations
- ▸Gardening: Finding the area of circular garden beds or pools
- ▸Engineering: Designing circular components and parts
- ▸Science: Calculating cross-sections and circular measurements
Frequently Asked Questions
What if I only know the diameter?
The radius is half the diameter. Simply divide the diameter by 2 to get the radius, then use the formula.
What is the difference between radius and diameter?
The radius is the distance from the center to the edge. The diameter is the distance across the circle through the center (2 × radius).
Why use π (Pi)?
Pi is a mathematical constant that represents the ratio of a circle's circumference to its diameter. It's approximately 3.14159.