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

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

P = 2Ï€r

Where:

P = Perimeter or Circumference of a circle

r = Radius of a circle

Letâ€™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 = 2Ï€r

P = 2 x 3.142 x 8

That is, P = 50.265

Therefore, the **perimeter or circumferenceÂ of a circle**Â isÂ **50.265 cm.**

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

The formula is P =Â Ï€d

Where:

P = Perimeter or Circumference of a circle

d = Diameter of a circle

Letâ€™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 =Â Ï€d

P = 3.142 x 10

So, 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} / _{2Ï€}

where;

r = Radius of a circle

P = Perimeter or Circumference of a circle

Letâ€™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} / _{2Ï€}

r = ^{16} / _{6.284}

Then, 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} / _{Ï€}

where;

d = Diameter of a circle

P = Perimeter or Circumference of a circle

Letâ€™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} / _{Ï€}

d = ^{20} / _{Ï€}

So, d = 6.365

Therefore, the **diameter of the circle** is **6.365 cm.**

### How to Calculate and Solve for the Perimeter or Circumference, Radius and Diameter of a Circle Using Nickzom Calculator

Nickzom Calculator â€“Â **The Calculator Encyclopedia**Â 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 theÂ **Nickzom Calculator â€“ The Calculator Encyclopedia.Â **First, you need to obtain the app.

You can get this app via any of these means:

**Web**Â â€“Â https://www.nickzom.org/calculator-plus

To get access to theÂ **professionalÂ **version via web, you need toÂ **register**Â andÂ **subscribeÂ **for**Â NGN 1,500Â **per**Â annum**Â to have utter access to all functionalities.

You can also try theÂ **demoÂ **version viaÂ https://www.nickzom.org/calculator

**Android (Paid)**Â â€“Â https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator

**Android (Free)**Â â€“Â https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator

**Apple (Paid)**Â â€“Â https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8

Once, you have obtained the calculator encyclopedia app, proceed to theÂ **Calculator Map,Â **then click onÂ **Mensuration****Â **under theÂ **Mathematics**Â section

Now, click on**Â Perimeter of a Circle**Â underÂ **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 parameterÂ which is the radius of the circle (r).

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

Finally, click onÂ **Calculate**

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