Board Foot Calculator

How it works

A board foot is a unit of volume: a piece of wood 1 inch thick, 12 inches wide and 12 inches long, or 144 cubic inches. Hardwood lumber is priced by the board foot because boards come in random widths and lengths, so pricing by the piece would not be fair to either side.

The calculator multiplies thickness and width in inches by length in feet and divides by 12. That gives the board feet in one piece; multiplying by the quantity gives the total, and the total times the price per board foot gives the cost.

Hardwood thickness is usually quoted in nominal quarters: 4/4 ("four-quarter") is 1 inch, 5/4 is 1¼ inches, 6/4 is 1½ inches and 8/4 is 2 inches. Enter the thickness in inches. The calculator uses exactly the dimensions you enter and does not convert nominal sizes to surfaced sizes.

Formula

board feet per piece = thickness (in) × width (in) × length (ft) ÷ 12
total board feet     = board feet per piece × quantity
total cost           = total board feet × price per board foot

Example

A 4/4 board (1 in thick) that is 6 in wide and 8 ft long contains 1 × 6 × 8 ÷ 12 = 4.00 board feet.

Ten of those boards at $6.50 per board foot come to 40.00 board feet and cost $260.00.

Assumptions and limitations

• Dimensions are used exactly as entered. If the yard measures rough-sawn stock before surfacing, enter the rough dimensions to match their count.
• Nominal quarter sizes (4/4, 5/4, 6/4, 8/4) are not converted; enter the thickness in inches.
• Waste, defects, kiln-drying charges and minimum-order surcharges are not included.
• Softwood dimensional lumber such as 2×4s is normally sold by the piece or linear foot, not by the board foot.

Frequently asked questions