Area and Perimeter > Circle

# Area and Perimeter: Circle

This online calculator is a free online tool to help you in calculate area and perimeter of Circle.

## Formula

- P – perimeter
- A – area
- r – radius

- d – diameter
- O – centre

You may need: Area and Perimeter of Square

## Circle

Circle is a round, two-dimensional shape, and all points on the edge have the same distance from the center of the circle. Circle is a closed shape. The distance from the center of the circle to any edge point of it is called radius (r). The longest distance from one end point of a circle to the other is called diameter, simply it is two times from the radius. To count/calculate the circle, do not forget to use the mathematical constant π (phi). The number of π is 3,14 or 22/7.

## The standard formula to count the Area of Circle

A=π.r^{2}

A= Area

π=3.14 or 22/7

r= radius

d= diameter (2 times of r or 2.r)

## The standard formula to count the Perimeter of Circle

P=π.d or 2.π.r

P= Perimeter

π=3.14 or 22/7

r= radius

d= diameter

## The Instruction and How to use the calculator online to count the Area and Perimeter of Circle

1. First, enter 1 value of r (radius) or d (diameter) of the Circle. This will automatically appear when you already input the value of radius / diameter.
2. Next, input how many round to decimal places you need. It can 1 or 2 or whatever you want.

3. After that, click the “Calculate” button and you will see the amount of Area A and Perimeter P on the section below.

4. To count another number, just input another radius / diameter like the first step.

## Example of the usage of calculator online to count the Area and Perimeter of Circle

1. Example, enter “7” in the column r (radius) of the Circle.

2. After that, click the “Calculate” button.

3. You will find the answer right there on the Area A column and Perimeter P column. The area is **153.94** and the Perimeter is **43.98**.