How to Calculate Board Feet: Formula, Examples, and Common Mistakes
Board Foot Calculator
Board foot = thickness (in) × width (in) × length (ft) ÷ 12. Enter nominal sizes as billed, or switch to actual measured sizes.
Estimate only. Species prices vary by yard, region and date. Confirm the final tally and price with your lumber supplier before ordering.
Formula: Board feet = thickness in inches x width in inches x length in feet, divided by 12. If all dimensions are in inches, divide by 144 instead.
Steps
1. Measure the thickness, width, and length of each board. 2. Multiply using the formula. 3. Multiply by the quantity of boards. 4. Add your waste allowance. 5. Multiply by the price per board foot to estimate cost.
Worked example
A board 1 inch thick, 6 inches wide, and 8 feet long is (1 x 6 x 8) / 12 = 4 board feet. Five boards are 20 board feet. Add 10 percent waste and you need 22 board feet.
Common mistakes
Forgetting waste, mixing nominal and actual sizes in one estimate, and pricing per board instead of per board foot.
Estimate only. Confirm with your supplier before ordering.