This calculator can be used to calculate the lineal foot factor for a board with a certain width. It can be used to easily calculate the lineal foot of boards needed to cover a wall or ceiling.
What you need to know to get the lineal foot factor is the exposed face of the board.
Exposed face = that part of the board you can see when multiple boards are installed.
First you need the square footage of the area, take the length and height (or width) of an area and multiply these by each other to get the square footage of the area you are planning to cover. Multiply this result of square footage by the lineal foot factor (LFF) of the board and the result will be lineal feet of boards needed.
Example wall length = 10' wall height = 9' exposed face of board= 4 1/2" = 2.67 LFF 10 * 9 * 2.67 = 240.3 lineal feet of board.