area online calculator that can calculate the area of a circle from its radius or from its diameter.

area_circle online

The calculator has several features allowing it to make **surface calculations**.
It is thus possible to calculate the surface of a circle, also called
area of a disc through area_circle function, but also the
surface of a rectangle
, or the
surface of a square
(which is a particular rectangle).

**Calculating the area of a circle** can be done from its
radius or its diameter.

The **area of a circle** is the **area** bounded by the **circle**.
The **area of a circle** is given by the **formula** `pi*r^2` where r represents the **radius of the circle**.

Thus, **calculating the area of a circle** with radius 3 is done by typing the following formula
area_circle(`3`) , after calculation, the result `9pi` is returned.

It is also possible to make **symbolic calculation** and **calculate the area of a circle** with radius 1+x, by typing
the following formula
area_circle(`1+x`) , after calculation, the result is returned.

If d is the diameter of the circle and its radius r, then the radius of a circle is equal to half of its diameter which is expressed by the formula `r=d/2`. From this formula, it is possible to determine the area of a circle from its diameter.

The **area of a circle** can be **calculated** from its **diameter** using the
**formula** `pi*(d/2)^2`, where d is the diameter of the circle.

Thus, **calculating the area of circle** with diameter 5 is done by entering the following formula
area_circle(`5/2`) , after calculation, the result `25/4*pi` is returned.

To apply the different calculation formulas, several quizzes on the calculation of the area of the square, the rectangle, and the circle are proposed.

area online calculator that can calculate the area of a circle from its radius or from its diameter.

See also

- Calculation of the area of a geometric figure. : area. Online area calculator which allows to calculate the area of a rectangle, square, triangle or circle.
- Area of a circle : area_circle. Area online calculator that can calculate the area of a circle from its radius or from its diameter.
- Area of a rectangle : area_rectangle. Area online calculator that can calculate the area of a rectangle from its length and its width.
- Area of a square : area_square. Area online calculator that can calculate the area of a square from the length of a side.
- Measurement conversions : convert. The measurement unit calculator allows online conversions volume, surface (area), length.
- Perimeter : perimeter. Online perimeter calculator that calculates rectangle perimeter, square perimeter, triangle perimeter or circle perimeter.
- Perimeter of a circle : perimeter_circle. Online calculator that calculates the perimeter of a circle from its radius.
- Perimeter of a rectangle : perimeter_rectangle. The online calculator allows to calculate the perimeter of a rectangle from its length and its width.
- Perimeter of a square : perimeter_square. The online calculator allows to calculate the perimeter of a square from the length of a side.
- Time converter : time_converter. Time calculator that can convert durations into seconds, minutes, hours and days.
- Volume of a cube : volume_cube. The online calculator allows to calculate the volume of a cube from the length of a side.
- Volume of a rectangular parallelepiped : volume_rectangle. The online calculator allows to calculate the volume of a rectangle from its length, its width and height.
- Volume of a sphere : volume_sphere. The online calculator allows to calculate the volume of a sphere from its radius.