Lumber Board Foot Calculator

A board foot is the standard unit for measuring and pricing hardwoods and rough-sawn lumber. One board foot equals 144 cubic inches, which is the volume of a piece 1 foot long, 1 foot wide, and 1 inch thick. The formula is: board feet = (thickness in inches x width in inches x length in inches) divided by 144. Knowing board feet lets you compare prices across different sizes and accurately calculate material cost before ordering.

For studs at 16-inch OC, use the formula: number of studs = (wall length in feet x 0.75) + 1. For 24-inch OC, use (length x 0.5) + 1. Add 3 extra studs per corner, 2 trimmer studs plus 2 king studs per door or window opening, and 1 extra stud per wall intersection. Plates: multiply wall length by 3 for one bottom plate and a double top plate. Add 10% for cuts and waste.

Use the formula: board feet = (nominal thickness x nominal width x length in feet) divided by 12. A 2x4 at 8 feet = (2 x 4 x 8) / 12 = 5.33 board feet. A 2x6 at 10 feet = (2 x 6 x 10) / 12 = 10 board feet. A 4x4 post at 8 feet = (4 x 4 x 8) / 12 = 10.67 board feet. Always use nominal dimensions (2x4, not 1.5x3.5) in this formula for correct results.

Construction-grade pine and SPF dimensional lumber typically runs $0.50 to $1.00 per board foot at big-box stores in 2025, though prices fluctuate with futures markets. Cedar costs $2 to $4 per board foot and is preferred for decks and outdoor projects. Common hardwoods range widely: poplar is $2 to $3, red oak $4 to $6, hard maple $5 to $8, and walnut $10 to $20 or more. Lumber yards often beat box-store prices on larger quantities.