# How to Calculate and Solve for the Perimeter or Circumference, Radius and Diameter of a Circle | The Calculator Encyclopedia

The image above is a circle.

To compute the perimeter or circumference of a circle, one essential parameter is needed and this parameter is the radius of a circle (r). You can also use the diameter of a circle to compute the area of a circle (d).

The formula for calculating the perimeter or circumference of a circle is:

P = 2πr

Where:

P = Perimeter or Circumference of a circle
r = Radius of a circle

Let’s solve an example:
Find the perimeter or circumference of a circle where the radius of a circle is 8 cm.

This implies that;
r = Radius of a circle = 8 cm

P = 2πr
P = 2 x 3.142 x 8
P = 50.265

Therefore, the perimeter or circumference of a circle is 50.265 cm.

Calculating the Area of a Circle using the Diameter of a Circle.

The formula is P = πd

Where:

P = Perimeter or Circumference of a circle
d = Diameter of a circle

Let’s solve an example:
Find the perimeter or circumference of a circle where the diameter of a circle is 10 cm.

This implies that;
d = Diameter of a circle = 10 cm

P = πd
P = 3.142 x 10
P = 31.42

Therefore, the perimeter or circumference of a circle with diameter is 31.42 cm.

How to Calculate Radius of a Circle when Perimeter or Circumference of the Circle is Given

r = P /

where;

r = Radius of a circle
P = Perimeter or Circumference of a circle

Let’s solve an example:
Find the radius of a circle where the perimeter or circumference of the circle is 16 cm.

This implies that;
P = Perimeter or Circumference of the circle = 16 cm

r = P /
r = 16 / 6.284
r = 2.55

Therefore, the radius of the circle is 2.55 cm.

How to Calculate Diameter of a Circle when Perimeter or Circumference of the Circle is Given

d = P / π

where;

d = Diameter of a circle
P = Perimeter or Circumference of a circle

Let’s solve an example;
Find the diameter of a circle where the perimeter or circumference of the circle is 20 cm

This implies that;
P = Perimeter or Circumference of the circle = 20 cm

d = P / π
d = 20 / π
d = 6.365

Therefore, the diameter of the circle is 6.365 cm.

Nickzom Calculator – The Calculator Encyclopedia is capable of calculating the perimeter or circumference of a circle.

To get the answer and workings of the perimeter or circumference of a circle using the Nickzom Calculator – The Calculator Encyclopedia. First, you need to obtain the app.

You can get this app via any of these means:

To get access to the professional version via web, you need to register and subscribe for NGN 1,500 per annum to have utter access to all functionalities.
You can also try the demo version via https://www.nickzom.org/calculator

Once, you have obtained the calculator encyclopedia app, proceed to the Calculator Map, then click on Mensuration under the Mathematics section

Now, click on Perimeter of a Circle under Mensuration

The screenshot below displays the page or activity to enter your value, to get the answer for the perimeter or circumference of a circle according to the respective parameter  which is the radius of the circle (r).

Now, enter the value appropriately and accordingly for the parameter as required by the example above where the radius of the circle is 8 cm.

Finally, click on Calculate

As you can see from the screenshot above, Nickzom Calculator – The Calculator Encyclopedia solves for the perimeter or circumference of a circle and presents the formula, workings and steps too.