The capacity of a dryer is measured by its drum volume in cubic feet. The size determines the amount of clothes that you can dry at a time. If you have a large family, or prefer to do laundry only on occasion, consider a larger dryer. Compact dryers can be as small as two cubic feet ,and extra-large dryers can exceed seven cubic feet. To calculate the volume, measure the depth and diameter of the dryer.
Measure the depth of the dryer from the back to the door opening.
Measure the diameter of the dryer.
Divide the diameter by two to find the radius. For example, if the diameter is three feet, the radius is 1.5 feet.
Calculate the size of the dryer by squaring the radius and multiplying by the depth. For example, if the radius is 1.5 feet and the depth is two feet, the volume is 4.5 cubic feet (1.5 x 1.5 x 2).