Calculating pipe area in square feet will help you find the volume of a particular pipe. All pipe volumes are designated in cubic feet. One cubic foot is equal to 7.48 gallons of liquid measure. Finding the overall volume of pipes can be an easy task once you understand the formula involved. The area of a circle is found by using the following equation: pi multiplied by the radius squared.

### Step 1

Measure the inside diameter of the pipe. In this case, the pipe can have a full diameter measurement of six inches. The radius measurement of the pipe then would be three inches.

### Step 2

Use the area formula described above and square the radius measurement of the six-inch pipe. This will entail multiplying three inches by three inches, which is equal to nine square inches. Now nine square inches by pi. This results in 28.27 square inches, the area in inches of the six-inch-diameter pipe.

### Step 3

Convert the total square-inch measurement into square feet. There are 144 square inches in one square foot. This is found by multiplying 12 inches by 12 inches. To find the square footage of 28.27 square inches, divide this number by 144. The result is 0.19 square feet.

### Step 4

Find the volume of a pipe that is 10 feet long. Multiply the area of 0.19 square feet by the overall length of 10 feet. The volume of the pipe is equal to 1.96 cubic feet.

### Step 5

Calculate the liquid capacity of the pipe in gallons. Multiply 1.96 cubic feet by 7.48 gallons per cubic foot. The six-inch diameter pipe that is 10 feet long will hold 14.68 gallons of liquid.