📏 Board Foot Calculator
Enter a board’s thickness, width and length to get its board feet, and the total (and cost) for any number of boards.
Total board feet
40 bf
Per board
4 bf
Total cost
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Board feet = thickness(in) × width(in) × length(ft) ÷ 12. A board foot is 144 in³ of wood. 🔒 In your browser.
How the board foot calculator works
A board foot is 144 cubic inches of wood, a piece 1 inch thick, 12 inches wide and 1 foot long. The formula is (thickness × width × length in inches) ÷ 144, or (thickness_in × width_in × length_ft) ÷ 12. Multiply by the number of boards, and by the price per board foot for the cost. Worked example: a piece of 8/4 (2-inch) hardwood, 8 inches wide and 6 feet (72 inches) long, is 2 × 8 × 72 ÷ 144 = 8 board feet; at $6 per board foot that board costs $48. Because board feet measure volume, doubling the thickness or the width doubles the board-foot count even though the length is unchanged.
Board feet measure volume, so a thicker board of the same face size counts as more. Hardwood is usually priced per board foot; softwood is often sold by the linear foot or piece.
Frequently asked questions
How do I calculate board feet?
Board feet = (thickness × width × length, all in inches) ÷ 144. A 1 × 6 board that’s 8 ft (96 in) long is 1 × 6 × 96 ÷ 144 = 4 board feet.
What is a board foot?
A unit of lumber volume equal to 144 cubic inches, nominally a board 1 inch thick, 12 inches wide and 1 foot long. It’s the standard way hardwood is sold in North America.
How is board foot different from linear foot?
A linear (running) foot measures length only; a board foot measures volume (thickness × width × length). Two boards of the same length but different widths have different board feet.
Should I use nominal or actual dimensions?
For rough (unplaned) hardwood, use the actual thickness (often quoted in quarters, e.g. 4/4 = 1 in). For dimensional softwood, note that nominal sizes (2 × 4) are larger than actual (1.5 × 3.5 in).
How do I work out the cost?
Multiply the total board feet by the price per board foot. Enter a price and the tool shows the total cost.
What does 4/4, 8/4 mean in lumber?
Hardwood thickness is quoted in quarter-inches: 4/4 is one inch, 8/4 is two inches, 6/4 is one and a half. These are the rough (pre-planed) thicknesses used to calculate board feet, so a planed 4/4 board that finishes near 13⁄16 inch is still sold and priced as a full 4/4 board foot.
How do I estimate board feet for a project?
Add up the board feet of every piece on your cut list, then add about 20-30% for waste from defects, trimming and mistakes. Buying by total board feet with a margin is more reliable than buying an exact count of boards, since hardwood comes in random widths and lengths.