Lumber Board Feet Calculator
This free board foot calculator converts your lumber dimensions into board feet and tells you the total cost. Enter thickness and width in inches, length in feet, how many boards you need, and optionally your price per board foot — results update instantly.
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Enter your board dimensions to see the board feet and total cost.
How to use this calculator
Enter the thickness and width in inches, the length in feet, and how many identical boards you need. Board-foot results appear instantly as you type, so you can try different sizes and compare on the fly.
If you know the lumber price, enter the price per board foot (many suppliers quote hardwoods this way). The calculator multiplies it by your total board feet to give an estimated material cost. Leave it at zero if you only want the volume.
Use the total board feet to comparison-shop: divide any quoted lumber price by its board footage to get the real cost per board foot, then compare that number across suppliers or species.
How it works
A board foot is a unit of lumber volume: 144 cubic inches, or a board 1 inch thick, 12 inches wide, and 1 foot long. Because the formula mixes inches and feet, dividing by 12 reconciles the units:
board feet = (T″ × W″ × L′) ÷ 12
For a 2×6 board 8 feet long: (2 × 6 × 8) ÷ 12 = 8 board feet. The total for your order is that per-board figure times your quantity, and the estimated cost is total board feet times your price per board foot.
Nominal vs actual: lumber is sold and priced by nominal size (a nominal 2×4 actually measures about 1.5″ × 3.5″). This calculator uses nominal dimensions, matching how suppliers quote prices. Costs are estimates — final pricing depends on the species, grade, and supplier.
Frequently asked questions
What is a board foot?
A board foot is a unit of lumber volume equal to a board 1 inch thick, 12 inches wide, and 12 inches long — 144 cubic inches in total. You can think of it as one linear foot of a 1×12 board.
How do I calculate board feet?
Multiply the board's thickness in inches by its width in inches by its length in feet, then divide by 12: board feet = (T″ × W″ × L′) ÷ 12. For example, a 2×6 board 8 feet long is (2 × 6 × 8) ÷ 12 = 8 board feet.
Should I use nominal or actual lumber sizes?
Lumber is bought and priced by its nominal size — the size it was before milling and drying — not its actual dimensions. A nominal 2×4 actually measures about 1.5″ × 3.5″, but it is priced as a 2×4. Use nominal dimensions in this board foot calculator for cost estimates; use actual dimensions only when comparing physical volume.
How many board feet are in a cubic foot?
Twelve. A board foot is 1/12 of a cubic foot (144 cubic inches), so divide your total board feet by 12 to get cubic feet. For example, 120 board feet equals 10 cubic feet.