If you wanted to ship something fragile in a box and needed to fill the space around the fragile item with packing peanuts then you would find it useful to be able to find the cubic feet of that box so that you know how much packing peanuts you will need. You might also want to know the volume of a box in cubic feet so that you know how much space in a storage unit you need to store the box. Whatever the reason, if you want to know how to find the cubic footage of a box then follow the steps below.
Things You'll Need
 Ruler
 Paper
 Pencil

Take your ruler and measure (in inches) the height (top to bottom), width (left to right), and depth (front to back) of the box that you wish to determine the cubic feet of.

Write your measurements down on a piece of paper.

Divide each measurement by 12, the number of inches in a foot, and write the resulting numbers down, including the unit label "ft." next to each measurement. For example, if you had a box that measured 24 in. x 12 in. x 36 in. then I would divide each of those three measurements by 12 and get the new measurements in terms of feet: 2 ft. x 1 ft. x 3 ft.

Multiply the 3 measurements that you just converted into feet together. For example, using the new measurements that we found in the previous step we would multiply 2 x 3 x 1 and get 6 as our answer.

Attach the unit label cubic feet to your answer and you have the volume of your box in cubic feet. So, for our example, the volume of the box in cubic feet would be 6 cubic feet.
Tips & Warnings
 You can also wait to convert from cubic inches to cubic feet at the end, rather than converting from inches to feet in the beginning. To do this you would multiply your measurements in inches together, and then divide the resulting number by 1728, which is 12 cubed, since that is how many cubic inches are in a cubic foot.