Board Foot Calculator

A board foot is a North American lumber-volume unit equal to a board twelve inches wide, twelve inches long, and one inch thick. That definition represents 144 cubic inches, not a particular board shape. A long narrow board and a short wide board can therefore contain the same number of board feet. Hardwood sellers, sawmills, cabinetmakers, and woodworkers commonly use the unit to compare rough lumber volumes and prices. When length is entered in feet and both width and thickness are entered in inches, board feet per piece equals length times width times thickness divided by twelve. The divisor is twelve because the length value is already in feet; converting it to inches and then dividing cubic inches by 144 simplifies to the same formula. The result is multiplied by quantity for the order total. One cubic foot contains twelve board feet, so total cubic feet equals board feet divided by twelve. If a price is supplied, estimated cost is total board feet multiplied by price per board foot. Use actual measured dimensions when estimating surfaced lumber. A nominal two-by-four is commonly about 1.5 inches thick and 3.5 inches wide, so an eight-foot piece contains 3.5 board feet rather than the volume implied by its nominal name. Rough-sawn hardwood may be sold by nominal thickness classes and measured using supplier-specific rounding or tally rules. Ask the seller whether measurements are taken before or after drying and surfacing, and whether fractions are rounded. The calculator assumes every piece has identical dimensions. For a mixed cut list, calculate each size as a separate group and add the totals. Purchase quantity should also allow for defects, grain matching, milling loss, crosscuts, and project waste. Board-foot cost covers lumber volume only; taxes, delivery, milling, minimum-order charges, and premium grades may change the invoice. Sheet goods are usually sold per sheet rather than by board foot, although their physical volume can still be expressed in board feet for comparison. Always confirm the supplier's tally before ordering expensive material.