This Area of Circle Calculator Online can be used to calculate the radius, diameter, circumference, area of a circle, area of ¼ circle, and area of ¾ circle. Just fill in one of the fields and the result will be displayed automatically.

## About Area of Circle Calculator Online

The Area of Circle Calculator Online is a tool that can be used to calculate circles. It is a free and easy-to-use online tool that you can use to measure the radius, diameter, circumference, area of a circle, area of ¼ circle, and area of ¾ circle.

The Circle Online Calculators will generate the answer to your question in just seconds, depending on what information you enter into it. You can use this math calculators for both metric and imperial measurements.

It does not require any installation or registration process, so you don’t need to worry about downloading anything or filling out lengthy forms before using it.

The Area Circle Online Calculators uses JavaScript, HTML, and CSS features on your browser’s rendering engine to calculate the area of circles without any use of plugins or extensions.

### Units in the Calculator

Keep in mind that the units of length shown in the calculator do not affect the calculations of the circle. But if you change the unit selection, then the values in the field will be converted to the selected units. For example, if the previously selected unit is inch (in), then you change to foot (ft), and the calculator will convert the value in the field from inch to foot.

The Units that can be selected in the calculator are inch (in), foot (ft), yard (yd), mile (mi), millimeter (mm), centimeter (cm), meter (m), and kilometer (km). If you don’t want to use units in the calculator, then you can choose none.

### Value of Pi (π)

The value of Pi (π) is the ratio of a circle’s circumference to its diameter. It is the most important mathematical constant and has been calculated to over a trillion decimal places.

Pi (π) is an irrational number, meaning that the digits after the decimal point are never-ending nor become repetitive. It can be approximated by 22/7, but this approximation does not always give an accurate answer for every decimal place.

The value of Pi (π) is 3.1415926535897932384626433832795028841971693993751… This is only 49 decimal places.

The value of Pi is used in calculating many things in math, physics, engineering, and other fields. It is used to calculate circumference and area, as well as volume and surface area.

The value of Pi used in the area of the circle calculator is 3.1415926535898. But you can also change the number of decimal places as desired from 3.14 onwards. For example, you can change it to 3.14 or 3.14159.

## How to Use The Area Circle Calculator?

You can use our calculator to find out everything there is to know about circles in a matter of seconds. You can, for example, calculate the formulas and see the area, radius, circumference, and diameter of any given circle.

- If you want to calculate the area of circle based on radius or diameter or circumference, just enter the value into the radius field or diameter field, or circumference field.
- If you want to calculate the diameter or radius, and circumference of the circle based on area, just enter the value into the area of the circle field or area of ¼ circle field or area of ¾ circle field.
- If you enter a value into one of the fields, the circle diameter calculator will calculate automatically for other fields.

## How to Calculate The Area of a Circle? The Formula for Calculating Area of Circles

This area of the circle calculator is designed to calculate the area of a circle. There are three formulas used in this calculator, namely, the radius formula, the diameter formula, and the circumference formula.

**The Radius Formula**

The radius formula is used when we know the radius of a circle and need to calculate its area.

Area of a Circle = π x radius^{2} or A = π x r^{2}

Area of ¼ Circle = ¼ x π x radius^{2 } or ¼A = ¼ x π x r^{2}

Area of ¾ Circle = ¾ x π x radius^{2 } or ¾A = ¾ x π x r^{2}

**The Diameter Formula**

The diameter formula is used when we know the diameter of a circle and need to calculate its area.

Diameter (d) = 2 x radius or d = 2 x r

Area of a Circle = π x (diameter/2)^{2} or A = π x (d/2)^{2}

**The Circumference Formula**

The circumference circle formulas is used when we know the circumference of a circle and need to calculate its area.

Circumference (c) = 2 x π x radius or c = 2 x π x r

Area of a Circle = π x (circumference /2π)^{2} or A = π x (c/2π)^{2}

### What is the Radius of Circle?

The radius is the distance from the center of a circle to any point on its circumference. The radius is always perpendicular to and bisects the diameter.

### What is the Diameter of Circle?

The diameter of a circle is the distance from one point on the circumference to another. It is measured along a straight line segment passing through the center of the circle and perpendicular to the plane of the circle.

### What is the Circumference of Circle?

The circumference of circle is the length around the edge of a circle. The circumference of a circle can be calculated by multiplying pi by the diameter of the circle.

### What is the Area of Circle?

The definition of a circle is a shape that has no endpoints and is made up of all the points on the circumference. The area of a circle is the amount of space it takes up, or how much it would cover if you put it on top of something.

The area of a circle is calculated by multiplying pi (3.14) by the radius squared (the distance from the center to any point on the circumference).

### How can this Area of Circle Calculator Online be helpful?

The circle area calculator will help you find the area of a circle by entering its radius or diameter. The area is calculated in square units. You can also enter the circumference and diameter, or use the circles radius to calculate circle circumference.

The Area of Circle Calculator Online can be helpful when you need to know how much space an object takes up, such as a garden or room, or when you are looking for information on how much material is needed for a project.