An Annulus is a shape made out of two circles.The region covered by two coincentric circles forms the Annulus Shape.
It share same center. Some of the real-life examples are finger-ring, dough-nut, etc. This Annulus Calculator will help
you to find 5 unknown variables by providing 2 known variables.

Select which value you are Providing (Outer Radius (r1), Inner Radius (r2), Outer Circumference (C1),
Inner Circumference (C2), Outer Circle Area (A1), Inner Circle Area (A2), Annulus Area (Ao)) input value and Click on Calculate .

##### Annulus

r1=Outer Radius

r2=Inner Radius

C1=Outer Circumference

C2=Inner Circumference

A1=Area of circle of r1

A2=Area of circle of r2

Ao=Shaded Area

Calculations Options

A Annulus Calculator help us to calculate different propertise of annulus shape . An Annulus is the shape between two concentric circle we get the value of Outer Radius(r1) , Inner Radius(r2) , Inner Circle Area(A2) , Outer Circle Area (A1), Inner Circumference(C1), Outer Circumference(C),Annulus Area(Ao) etc . We can find the value of Five Unkown variables only if value of Two variables are known .By using following Formula :

**Outer Circumference : **
C_{2} = 2pr_{2}

Where

C _{2} = Outer Circumference

r _{2} = Outer Radius

**Inner Circumference : **
C_{1}= 2pr_{1}

Where

C _{1} = Inner Circumference

r _{1} = Inner Radius

**Inner Surface Area :**
A_{1} = pr_{1}^{2}

Where

r _{1} = Inner Radius

A_{1} = Inner Surface Area

**Outer Surface Area :**
A_{2} = pr_{2}^{2}

Where

r _{2} = Outer Radius

A_{2} = Outer Radius

**Annulus Surface Area :**
A_{o} = A_{1} - A_{2}

Where

A_{1} = Inner Surface Area

A_{2} = Outer Surface Area

### How to use Annulus Calculator?

Step by step procedure for Annulus Calculator is as follows.

**Step 1: **Select which value you will be providing? Dropdown has Outer Radius(r1) and Inner Radius(r2), Outer Radius(r1) and Inner Circumference(C2), Outer Radius(r1)and Inner Circle Area(A2), Inner Radius(r2) and Outer Circumference(C1), Outer Circumference(C1) and Inner Circumference(C2), Outer Circumference(C1) and Inner Circle Area(A2), Inner Radius(r2) and Outer Circle Area(A1), Inner Circumference(C2) and Outer Circle Area(A1), Outer Circle Area(A1) and Inner Circle Area(A2), Annulus Area(Ao) and Outer Radius(r1), Annulus Area(Ao) and Inner Radius(r2), Annulus Area(Ao) and Outer Circle Area(A1), Annulus Area(Ao) and Inner Radius(A2), Annulus Area(Ao) and Outer Circumference(C1), Annulus Area(Ao) and Inner Circumference(C2) options.

**Step 2: **Input appropriate value as per selected type in Step 1.

**Step 3: **Now click on "Calculate" button to get result.

You will get Outer Radius(r1), Inner Radius(r2), Outer Circumference(A1), Inner Circumference(A2), Outer Circle Area(A1), Inner Circle Area(A2), Annulus Area(Ao) as per you selection and value input.