What is a Board Foot?

A board foot is a unit of measure for lumber in the form of a foot-long board and is used to determine the cost, quantity, and other aspects of lumber materials. It is one of the most commonly used measurements in the building industry. One board foot is equal to a piece of wood that measures one foot in length, twelve inches in width, and one inch in thickness. In some cases, board feet can even be measured as a fractional foot measure such as two and a half inches for width and a quarter inch for thickness.

How it is Measured

The board foot is not figured by simply multiplying length times width times thickness. To accurately measure a board foot, the formula of length in feet times width in inches divided by 12 times thickness in inches is used. As an example, a board measuring 10 feet long, 5 inches wide and 3/4 inch thick would be measured as follows- 10 x 5/12 x 3/4 = 41.6 board feet.

Uses of a Board Foot

In the worlds of construction and building, the board foot is arguably the most important unit of measure for lumber because it is often used to determine the total amount of material needed and the cost of the material being purchased. For example, if a customer needs 20 board feet of wood and the price is $0.90 per board foot, the overall cost to purchase the lumber would be $18.00. The board foot measurement is also used to determine waste, as a sawyer or mill worker may need to cut pieces of lumber to a customer’s specifications. The sawyer knows the total board footage coverage available, and is able to estimate how much waste each cutting job will create.