# Area of a Circle Calculator

Use the this circle area calculator below to find the area of a circle given its radius, or other parameters. To calculate the area, you just need to enter a positive numeric value in one of the 3 fields of the calculator. You can also see at the bottom of the calculator, the step-by-step solution.

### Area of a Circle Calculator

## Formula for area of a circle

Here a three ways to find the area of a circle (formulas):

### Circle area formula in terms of radius

### Circle area formula in terms of diameter

### Circle area formula in terms of circumference

See below some definitions related to the formulas:

### Circumference

Circumference is the linear distance around the circle edge.

### Radius

The radius of a circle is any of the line segments from its center to its perimeter. The radius is half the diameter or r = ^{d}/_{2}.

### Diameter

The diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. The diameter is twice the radius or d = 2r.

### The Greek letter π

π represents the number Pi which is defined as the ratio of the circumference of a circle to its diameter or π = ^{C} / _{d}. For simplicity, you can use Pi = 3.14 or Pi = 3.1415. Pi is an irrational number. The first 100 digits of Pi are: 3.1415926535 8979323846 2643383279 5028841971 6939937510 5820974944 5923078164 0628620899 8628034825 3421170679 ...

### Note:

If you input the radius in centimeters, you will get the answer in square centimeters (cm²), if in inches, will get the answer in square inches (in²) and so on ...

Circumference is often misspeled as circunference.

You can use our area unit converter to see the results in other units.

## Sample Circle Area Calculations

- Area of a Circle with diameter 33 units
- Area of a Circle with circumference 9.4 kilometers
- Area of a Circle with diameter 4138 meters
- Area of a Circle with circumference 10.2
- Area of a Circle with circumference 15 miles
- Area of a Circle with circumference 50.24 yard
- Area of a Circle with diameter 14.4 units
- Area of a Circle with circumference 2.3 yard
- Area of a Circle with radius 14.8 miles
- Area of a Circle with circumference 4.4 meters

- Area of a Circle with diameter 16.4 units
- Area of a Circle with diameter 3.8 kilometers
- Area of a Circle with circumference 7.1 yard
- Area of a Circle with radius 0.5 kilometers
- Area of a Circle with diameter 75 centimeters
- Area of a Circle with circumference 16.1 inches
- Area of a Circle with circumference 11.5 kilometers
- Area of a Circle with circumference 12 inches
- Area of a Circle with diameter 61
- Area of a Circle with diameter 14.9 kilometers

- Area of a Circle with diameter 19.6 mm
- Area of a Circle with radius 18.4 mm
- Area of a Circle with radius 4.2 miles
- Area of a Circle with diameter 5.2 meters
- Area of a Circle with radius 4.3 inches
- Area of a Circle with diameter 18.3 feet
- Area of a Circle with diameter 8.3 miles
- Area of a Circle with circumference 16.5 feet
- Area of a Circle with diameter 3.6 miles
- Area of a Circle with diameter 14.2 units