Board feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12
For multiple pieces: add the board feet of each piece
For rough lumber: use the actual dimensions you are measuring
For nominal lumber: use the nominal dimensions if that is how it is sold
For one board: Board feet = (T × W × L) ÷ 12
Example: 2 in × 6 in × 8 ft = 8 board feet
Example: 1 in × 12 in × 10 ft = 10 board feet
Example: 2 in × 4 in × 12 ft = 8 board feet