A corner shelf is one that fits neatly into any square corner of a room. Whether you are designing and building your own corner shelf unit or you have a ready-made shelf already occupying a corner of a room, you may wish to determine how much storage space a shelf or series of shelves will provide. You can calculate the size of a corner shelf by using basic math formulas and adding the answers together.

## Step 1

Measure the dimensions of the shelf -- most corner shelves have one of two shapes: triangle or quarter circle. Measure the depth, the front edge and the side edges with the tape measure.

## Step 2

Calculate the area of a triangular shelf by dividing the front edge by 2 and multiplying it by the depth of the shelf (from the inner corner out to the front edge). For example, if the front edge is 20 inches and the depth of the shelf is 8 inches, calculate the following: 20 / 2 = 10; 10 * 8 = 80 inches. The surface area of the triangular shelf is 80 inches.

## Step 3

Calculate the area of a quarter-circle shelf by multiplying the left or right straight edge of the shelf by itself. Multiply the answer by 3.14 and then divide the answer by 4. For example, if the straight edge is 8, calculate the following: 8 * 8 = 64; 64 * 3.14 = 200.96; 200.96 / 4 = 50.24 inches. The surface area of the quarter-circle shelf is 50.24 inches.

## Step 4

Multiply the surface area for one shelf by the number of shelves. For example, if you have four triangular shelves, multiply 80 * 4 = 320 inches for the entire corner shelf unit. If you have three quarter-circle shelves, multiply 50.24 * 3 = 150.72 inches for the entire corner shelf unit.