Measure the length, width and height of the box with a measuring tape in inches. Write down the measurements.
Multiply the length by the width by the height of the box, using a calculator to find volume in cubic inches. For example, if the length is 5 inches, the width 4 inches and the height 3 inches, V = 5 X 4 X 3, or 60 cubic inches. Write down the result.
Divide the result by 1728, the cubic inch equivalent to a cubic foot, to convert cubic inches to cubic feet. For example, if the volume of the box is 60 cubic inches, divide 60 by 1728 to obtain the result in cubic feet. Write down the result.
Round the result to nearest two decimal points. In the example, the volume equals 0.034722222 cubic feet. Rounded to the nearest two decimal points, the result is 0.03 cubic feet.