Board Foot Calculator
Hardwood lumber is sold by the board foot — a volume measure equal to a board 1 inch thick, 12 inches wide and 1 foot long. Enter your dimensions and quantity to get the total board footage you need to order and price.
Your answer
How it works
Formula
Board Feet = (Thickness × Width × Length(ft) ÷ 12) × Quantity
Worked example
Ten boards of 1 × 6 × 8 ft red oak = (1 × 6 × 8 ÷ 12) × 10 = 40 board feet.
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How to calculate board feet
A board foot is a volume measure: one board 1 inch thick × 12 inches wide × 12 inches long, or 144 cubic inches. Two equivalent formulas: (1) if length is in feet, Board Feet = (Thickness_in × Width_in × Length_ft) ÷ 12; (2) if every dimension is in inches, Board Feet = (Thickness_in × Width_in × Length_in) ÷ 144. Multiply by the piece count to get total footage. Always use nominal thickness (4/4 = 1 in, 8/4 = 2 in) — hardwood is priced at nominal even after it has been planed thinner.
Understanding the quarter system
Hardwoods are sold in quarter-inch thickness increments. 4/4 (four-quarter) is 1 in rough, 5/4 is 1-1/4 in, 6/4 is 1-1/2 in, 8/4 is 2 in, 10/4 is 2-1/2 in, 12/4 is 3 in. Rough lumber comes 'in the rough' at those nominal thicknesses; S2S (surfaced two sides) or S4S (surfaced four sides) is planed about 3/16 to 1/4 inch smaller than nominal but priced at nominal thickness. Order 4/4 rough if you plan to plane it yourself; order S2S for ready-to-use furniture stock.
How much waste should you order?
Rough hardwood is never defect-free. Plan on ordering 25–40% more board feet than the parts list requires: 20–25% for high-select grades (FAS), 30–40% for #1 Common. Long, wide, defect-free parts drive the multiplier up. If your part list totals 20 bf, order 26–28 bf of FAS or 27–30 bf of #1 Common. Always crosscut to rough length + 1 inch and rip to rough width + 1/2 inch before jointing.
Worked example
You need eight 3/4-in × 5-in × 30-in table apron pieces from red oak. Convert: 4/4 nominal thickness, 5 in wide, 2.5 ft long, 8 pieces. Board feet = (1 × 5 × 2.5 ÷ 12) × 8 = 8.33 bf net. Add 30% waste for #1 Common grade → 10.83 bf. At $7/bf that is about $76 in lumber.