Q & A: Board Feet Calculation - Popular Woodworking Magazine

## Q & A: Board Feet Calculation

### Q:

I used to buy planed and jointed lumber (S4S) at a home center where it was sold by the lineal foot.Now that I have a planer and jointer, I want to buy my lumber in the rough but I’m confused. It’s sold by the “board foot.” What does board foot (bd. ft.) really mean and how do I calculate it?

### A:

Lineal feet is a measure of length.
Board feet is a measure of volume. In
the same way that sand is sold by the
cubic yard, rough lumber is sold by the
board foot.

Calculating board feet for 4/4 (1-in.
thick) lumber is easy. Simply figure out
the board’s surface measure:

Full width in inches times length in
feet divided by 12.

“Full width” is rounded up or down
to the nearest whole inch. “Length in
feet” is a whole number, too. Board feet
are rounded to the nearest whole foot.

To calculate the number of board
feet in a thicker board, multiply the
surface measure by the thickness of
the board.Here’s an example for a 6/4
(1-1/2-in. thick) board that’s 7-3/8-in.
wide and 8 ft. 3-in. long:

Board feet = (W x L x TH)/12
= (7 x 8 x 1-1/2)/12

= 7 board feet

For your calculations, be sure to