Board feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12
Board feet = (Thickness in inches × Width in inches × Length in inches) ÷ 144
Round measurements to the desired precision before calculating
Use the actual dimensions, not nominal dimensions
For multiple boards, calculate each board foot amount and add them together
For rough lumber, use thickness in quarters as actual thickness in inches
For example: 1 in × 6 in × 8 ft ÷ 12 = 4 board feet
For example: 2 in × 4 in × 10 ft ÷ 12 = 6.67 board feet
For example: 0.75 in × 5.5 in × 12 ft ÷ 12 = 4.13 board feet