The foot cubed, also called the cubic foot, is the unit of volume in the English foot-pound-second ( fps ) system. The symbol for foot/feet cubed is ft 3 . Less formally, cubic foot/feet is sometimes abbreviated cu ft.
Material density, more often referred to simply...(WhatIs.com)
It is important to understand that volume is proportional to the cube of the linear dimension. Thus, if all linear dimensions are tripled, the volume becomes 27 times (3 3 ) as great; if all linear dimensions are cut to 1/12, the volume becomes 1/1,728 (1/12 3 ) as great. A volume of 1 ft 3 is therefore equal to 1/27 yard cubed (1/27 yd 3 ) or 1,728 inches cubed (1,728 in 3 ).
When converting between feet cubed and metric units of volume such as the meter cubed (m 3 ) or the centimeter cubed (cm 3 ), the linear-unit conversion factor must be cubed. For example, 1 m is approximately 3.281 ft; therefore 1 m 3 = 3.281 3 ft 3 = 35.3 ft 3 (approximately). Conversely, 1 ft is approximately 0.3048 m; therefore 1 ft 3 = 0.3048 3 m 3 = 0.0283 m 3 (approximately).