Board Foot Calculator
Calculate board feet of lumber from dimensions for pricing and quantity estimation. Enter values for instant results with step-by-step formulas.
Formula
Board Feet = (Thickness in. x Width in. x Length ft.) / 12
One board foot equals 144 cubic inches of wood, or a piece 1 inch thick, 12 inches wide, and 12 inches long. When length is in feet, divide by 12 instead of 144. Multiply board feet per piece by quantity for total, then by price per BF for cost.
Worked Examples
Example 1: Dining Table Top Material
Problem: You need 8 boards of walnut, each 8/4 thick (2 inches), 8 inches wide, and 6 feet long at $14 per board foot. How many board feet and what is the total cost?
Solution: Board feet per piece = (2 x 8 x 6) / 12 = 96 / 12 = 8 BF\nTotal board feet = 8 BF x 8 pieces = 64 BF\nTotal cost = 64 BF x $14/BF = $896\nPlus 20% waste: 64 x 1.2 = 76.8 BF = $1,075.20
Result: 64 board feet needed | $896 base cost | ~77 BF with waste ($1,075)
Example 2: Bookshelf Project in Cherry
Problem: Calculate board feet for 12 pieces of 4/4 cherry, 6 inches wide, 4 feet long at $9 per board foot.
Solution: Board feet per piece = (1 x 6 x 4) / 12 = 24 / 12 = 2 BF\nTotal board feet = 2 BF x 12 pieces = 24 BF\nTotal cost = 24 BF x $9/BF = $216\nCost per piece = 2 BF x $9 = $18
Result: 24 board feet total | $216 cost | $18 per piece
Frequently Asked Questions
What is a board foot and how is it measured?
A board foot is the standard unit of measurement for hardwood lumber in North America. It represents a piece of wood that is one inch thick, twelve inches wide, and twelve inches long, which equals 144 cubic inches of wood. Board feet measurement accounts for the three-dimensional volume of lumber rather than just the surface area. This system allows lumber yards and woodworkers to price wood consistently regardless of the board dimensions. Unlike construction lumber that is sold by the linear foot in standard dimensions, hardwood is almost always sold by the board foot because boards come in random widths and lengths that vary from piece to piece.
How do you calculate board feet for a piece of lumber?
The board foot formula is: Board Feet = (Thickness in inches x Width in inches x Length in inches) / 144. For convenience, when length is measured in feet instead of inches, the formula becomes: Board Feet = (Thickness x Width x Length in feet) / 12. For example, a board that is 2 inches thick, 8 inches wide, and 10 feet long contains (2 x 8 x 10) / 12 = 13.33 board feet. When calculating for rough lumber, use the actual dimensions. For surfaced lumber (S2S or S4S), you may still be charged based on the rough dimensions before planing. Always confirm with your lumber supplier which dimensions they use for pricing.
Why is hardwood lumber sold by the board foot instead of linear feet?
Hardwood lumber is sold by the board foot because hardwood boards come in random widths and lengths, unlike dimensional softwood lumber that is milled to standard sizes. When a hardwood log is sawn, each board has a different width depending on where it was cut from the log and how the grain runs. Selling by the board foot creates a fair pricing system where you pay for the actual volume of wood you receive regardless of the board dimensions. This also allows customers to mix and match different width boards for their projects while paying a consistent price per unit of wood. Construction softwood like two-by-fours and two-by-sixes are standardized sizes, so they can be priced simply per linear foot or per piece.
How do I convert between board feet and other measurements?
Converting between board feet and other units is straightforward once you understand the relationships. One board foot equals 144 cubic inches, or 1/12 of a cubic foot. To convert board feet to cubic feet, divide by 12. To convert cubic feet to board feet, multiply by 12. For square footage coverage, the conversion depends on board thickness. One board foot of 4/4 lumber covers one square foot, one board foot of 8/4 lumber covers only half a square foot, and one board foot of 1/2-inch material covers two square feet. When estimating material for a project measured in square feet, multiply the square footage by the thickness in inches to get the approximate board footage needed. Always add waste allowance to your final calculation.
How do I interpret the result?
Results are displayed with a label and unit to help you understand the output. Many calculators include a short explanation or classification below the result (for example, a BMI category or risk level). Refer to the worked examples section on this page for real-world context.
How accurate are the results from Board Foot Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.