Measure the length, width, and height of the space in feet
Multiply length × width × height
Use the formula: cubic feet = L × W × H
If measurements are in inches, divide each by 12 before multiplying
If the shape is not a rectangular box, break it into simpler shapes and add the cubic feet together
For cylinders, use the formula: cubic feet = π × radius² × height
For irregular objects, estimate by using the closest simple shape or by water displacement converted to cubic feet