Use a tape measure to measure the outside length of your home.
Measure the width of your home.
Measure the height of your house from floor to ceiling.
Convert all measurements to feet. For instance, if your width is 50 feet, 6 inches, divide 6 by 12 (for 12 inches in a foot) to get 0.5. Therefore, this measurement would be 50.5 feet.
Multiply the width times the length times the height of your home. For instance, if your home is 80 feet long, 50 feet wide and 10 feet high, multiply 80 times 50 times 10 to get 40,000 cubic feet.