Lumber Cost Calculator
Lumber priced by the board foot is easy to cost once you know your board feet and the price. The catch is waste: offcuts, defects, and squaring losses mean you must buy more than the finished parts contain. This calculator multiplies your board feet by an optional waste allowance, then by the price per board foot, to give the board feet to purchase and the total material cost. Enter the price exactly as quoted; tax and delivery are extra.
Lumber cost formula
board feet to buy = finished board feet * (1 + waste percent / 100)
total cost = board feet to buy * price per board foot
The waste allowance scales up the board feet you must purchase. Multiplying by the price per board foot gives the material cost before tax and delivery.
Worked example
A project needs 20 board feet finished, with a 25 percent waste allowance and a price of 6.50 per board foot. Board feet to buy = 20 * 1.25 = 25.00. Total cost = 25 * 6.50 = 162.50. Lowering waste to 10 percent for cleaner stock drops the buy to 22 board feet and the cost to 143.00.
Lumber cost: frequently asked questions
How is lumber cost calculated?
Lumber sold by board foot costs the board feet multiplied by the price per board foot. To account for offcuts, knots, and squaring losses, add a waste percentage, which increases the board feet you must buy. Total cost equals board feet times (1 plus waste percent over 100) times price per board foot.
What waste allowance should I add?
It depends on the project and the lumber grade. Rough hardwood with defects to cut around often needs 20 to 40 percent extra; clean pre-dimensioned stock needs little or none. The right figure is your call based on your cut list and yield, so it is a user-editable input here.
Where do I get the board feet?
Calculate board feet from the thickness, width, and length of your boards using the board foot formula (thickness times width times length in inches, divided by 144). Use our board feet calculator first, then enter the total board feet and your price here.
Does this include tax or delivery?
No. The result is the material cost before sales tax, delivery, or milling charges. Add those separately if your supplier applies them. Enter the price per board foot exactly as quoted so the material total is accurate.
Sources and method
- The cost is board feet times price with a waste multiplier; it is arithmetic, not a sourced figure. Enter the board foot price your supplier quotes.
- USDA Forest Service Forest Products Laboratory: Wood and lumber measurement research (board foot definition).
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.