A measurement of 48 inches is equivalent to 4 feet. Converting from inches to feet can be done by dividing the number of inches by 12, as 12 inches is equivalent to 1 foot.
In historical English customary measurement systems, certain distance units such as inch and foot were based on the dimensions of certain human body parts. The inch represented the width of a human thumb, and the foot represented the length of a human foot. In some languages, the word for "inch" and the word for "thumb" are the same. Furthermore, in the 14th century, King Edward II declared an inch to be equivalent to the length of three grains of barley measured end-to-end.