Why do we call 12 inches a foot?
The foot as a unit of measurement gets its name because it may first based on the length of the human foot.
Long ago, people didn’t have rulers to measure with. Instead, they used such handy “rulers” as the human foot or hand (an inch was the breadth of the thumb).
The ancient Romans divided their foot measurement into 12 “unicae” (inches).
The English borrowed the old Roman measurement. However, they made their foot the length of the king’s foot and measured an inch as the length of three grains of barley laying end-to-end.
Of course, such measurements were not always accurate. Same barley grains and some kings’ foot were longer than others.
To solve this problem, it was eventually decided to make standard units in which every foot and each inch were just too long
Today, when you measure foot and inches with a ruler, you will be sure of getting the same answer every time. – Dick Rogers