How to Find the Cubic Feet of an Attic

Divide the floor space of your attic into rectangular areas. This will make the calculations easier. For instance, if your attic is in the shape of an “L,” then divide it into one long rectangle and one short rectangle.

Measure the length of each rectangle and record it. Measure the width of each rectangle and record it. Make all of your measurements in feet.

Multiply the width of each rectangle by its length. Add the results together. This result is the total area of your attic floor.

Measure the height of the ceiling, if your attic has a flat ceiling. Multiply the result by the area of the attic floor. This result is the volume of your attic in cubic feet.

Measure the distance from the floor to the lowest part of the ceiling and record it. Multiply this distance by the area of the attic floor. The result of this is the volume of the lower part of your attic.

Measure the distance from the floor to the highest point of the ceiling and record it. Use a ladder if necessary to reach it.

Divide the area under the roof into triangular sections, running from the lowest point in the ceiling to the highest. Do this for each rectangular section.

For each triangle, measure the distance from the wall where the ceiling is lowest to the point on the floor under the peak of the roof. This is the length of the base of the triangle.

Subtract the height of the lowest part of the ceiling from height of the peak of the ceiling. This is the height of the triangle. Multiply the base of each triangle by its height. Divide the result by two. Multiply this result by the length of the section. Do this for each section. Add the results for each section together. This result is the upper volume of the attic. Add the upper and lower volumes to get the total volume.