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Free board foot calculator. Convert lumber dimensions to board feet, estimate waste, and price hardwood, softwood, and framing material.
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Enter measured project values. Results update only when you choose Calculate.
Method
A 16-ft 2x10 contains 26.67 board feet: 2 x 10 x 16 / 12. Run the same math on its actual dressed face - 1.5 in x 9.25 in - and you get 18.5 board feet, a 31% shortfall. Board feet are figured on nominal dimensions, and estimators who forget that come up short on every beam package and hardwood order they price.
Board-foot math shows up wherever lumber is sold by volume instead of by the piece: timber and beam packages, custom millwork, hardwood for trim and stair parts, and anything bought rough from a sawmill or wholesaler. It is also how you settle the supplier-quote shootout - one yard quotes per board foot, another per linear foot, a mill quotes per thousand board feet (MBF), and the only way to compare them is to convert everything to the same unit before you commit a PO.
For dimensional softwood, use the trade name: a 2x4 counts as 2 in x 4 in even though it dresses out at 1.5 in x 3.5 in. For hardwood, use the rough thickness in quarters - 4/4 is 1 in, 8/4 is 2 in - measured before surfacing, not after.
Multiply thickness (in) x width (in) x length (ft) and divide by 12. An 8-ft 2x6 is 2 x 6 x 8 / 12 = 8 board feet. Total each size and length separately so the yard can pull the order without calling you back.
If one supplier prices per board foot and another per linear foot, convert before comparing: price per LF = price per BF x thickness x width / 12. A 2x12 quoted by the linear foot hides twice the wood of a 2x6 at the same length, so per-LF numbers alone tell you nothing.
Add 5-10% on clean stock cut to length, and 15-30% on hardwood or rough-sawn material you will rip, joint, and cut around knots and checks. Character-grade lumber and long clear runs (stair skirts, mantels) sit at the high end because one defect can kill a whole board.
Multiply thickness in inches by width in inches by length in feet, then divide by 12. A 2x10 that is 16 ft long is 2 x 10 x 16 / 12 = 26.67 board feet. If all three dimensions are in inches, divide by 144 instead - the result is the same.
An 8-ft 2x4 contains 5.33 board feet (2 x 4 x 8 / 12). A 10-footer is 6.67 BF, a 12-footer is 8 BF, and a 16-footer is 10.67 BF. Use the nominal 2x4 dimensions, not the actual 1.5 in x 3.5 in dressed size.
Use nominal dimensions for softwood dimensional lumber - a 2x4 is calculated as 2 in x 4 in even though it measures 1.5 in x 3.5 in after surfacing. Hardwood is different: it is measured on the rough-sawn size before planing, quoted in quarters (4/4 = 1 in, 8/4 = 2 in). Either way, the billed size is larger than the wood you actually take home.
A linear foot measures only length; a board foot measures volume (1 board foot = a 12 in x 12 in x 1 in piece, or 144 cubic inches nominal). To convert, multiply price per board foot by thickness x width / 12: a 2x6 priced at $3.00/BF works out to $3.00 x 2 x 6 / 12 = $3.00 per linear foot. Always convert both quotes to the same unit before deciding which supplier is cheaper.
For select or better softwood cut to stock lengths, 5-10% covers end trim and the odd split. For hardwood or rough-sawn stock you plan to rip and joint, plan on 15-30% depending on grade - lower grades carry knots, wane, and checks that you cut around. Long clear runs like stair skirts or countertops push waste higher because one defect can condemn a whole board.
A board foot is the standard unit of lumber volume in North America, equal to 144 cubic inches — the volume of a board 1 inch thick, 12 inches wide, and 12 inches long. Lumber yards, sawmills, and hardwood dealers price most hardwood and rough lumber by the board foot.
Understanding how to calculate board feet is essential for cabinet shops, framers, deck builders, woodworkers, and anyone bidding lumber-intensive projects.
The board foot exists because lumber is a three-dimensional material sold by volume rather than length. A 1 x 12 x 12 inch piece and an 8 inch wide x 1.5 inch thick x 18 inch long piece both contain one board foot of wood, even though they look completely different. By standardizing on volume, suppliers can price oak, walnut, cherry, and exotic species fairly across the wide range of widths and thicknesses they stock. Softwood framing lumber such as 2 x 4 and 2 x 6 is usually priced per piece, but board feet still appears on bid sheets, freight invoices, and timber takeoffs.
Contractors use board foot calculations to compare supplier quotes, build accurate construction estimates , set markups for profitability, and reconcile delivered quantities against the takeoff. A small error in board foot accounting compounds across hundreds of pieces, so the math has to be right before you submit a quote.
The board foot formula is straightforward once you commit it to memory:
Board Feet = (T x W x L) / 12
T = Thickness in inches · W = Width in inches · L = Length in feet
If your length is measured in inches instead of feet, divide by 144 rather than 12. The number 144 is simply 12 x 12, which converts the volume from cubic inches into board feet (one board foot equals 144 cubic inches).
Worked example: Calculate the board feet for a kitchen cabinet job using 4/4 cherry. The takeoff shows 30 boards, each 6 inches wide and 8 feet long. Thickness for 4/4 stock is 1 inch. Per board: 1 x 6 x 8 / 12 = 4 board feet. Total: 30 boards x 4 board feet = 120 board feet. Add a 20 percent waste factor for hardwood: 120 x 1.20 = 144 board feet. At $9.50 per board foot, the cherry budget is $1,368, plus freight and any S4S milling charges.
Mixed sizes: When the order contains different dimensions, calculate each group separately and sum. For a deck framing package with 24 pieces of 2 x 8 x 12 (24 x 16 = 384 BF), 16 pieces of 2 x 10 x 12 (16 x 20 = 320 BF), and 8 pieces of 4 x 4 x 8 (8 x 10.67 = 85.36 BF), the total is 789.36 board feet before waste. Track each group on your takeoff so you can verify the delivery line by line.
Quarter notation: Hardwood thickness is expressed in quarters of an inch. 4/4 = 1 inch, 5/4 = 1.25 inches, 6/4 = 1.5 inches, 8/4 = 2 inches, 12/4 = 3 inches, 16/4 = 4 inches. When you read a hardwood quote that says "5/4 x random width x random length, $7.25/BF," the 5/4 is your thickness in the formula even though the board may surface to about 1.0625 inches.
A custom millwork shop quotes a wainscoting job using 4/4 FAS red oak at $6.75 per board foot. 1,000 BF x $6.75 = $6,750 in lumber alone. Add 22 percent waste for defect cuts and grain matching ($1,485), $250 freight, and $0.40 per BF for S4S milling ($400). Total delivered material cost: $8,885. The shop adds a 35 percent markup for overhead and profit, bringing the wainscoting line item to $11,995.
A 2 x 4 x 8 contains 5.33 board feet on paper, but the actual milled size is 1.5 x 3.5 x 96 inches, which is only 3.5 board feet of real wood. The board foot calculation uses nominal dimensions because that is the industry convention for softwood pricing and supplier quotes. When comparing costs across nominal and actual measurement systems, always confirm which one applies to the quote.
A kitchen cabinet build uses 180 BF of 4/4 hard maple at $7.10/BF ($1,278), 60 BF of 8/4 hard maple at $9.85/BF ($591), and 24 BF of 4/4 walnut for accent panels at $13.50/BF ($324). Lumber subtotal: $2,193. With 20 percent waste built in and freight, the total cabinet lumber budget reaches roughly $2,800.
A 16 x 20 deck frame uses 30 pieces of 2 x 8 x 16 joists (640 BF), 6 pieces of 2 x 10 x 16 beams (160 BF), and 8 pieces of 4 x 4 x 8 posts (85.3 BF). Total: 885.3 BF. At $1.45 per BF for pressure-treated southern yellow pine, the framing lumber lands at $1,283 plus delivery. Use our deck cost calculator for the full project including decking and railings.
A 2 x 4 is calculated as 2 x 4 even though the actual size is 1.5 x 3.5. Suppliers price on nominal, so your takeoff should match.
Rough hardwood is sold at full nominal thickness; S4S surfaced lumber loses about 1/4 inch but is still priced at the original BF count. Confirm before you sign the PO.
Skipping the divisor is the most common math error. The result will be off by a factor of 12, often hidden inside a large takeoff total until the invoice arrives.
Hardwood projects need 20-30 percent waste because of defect cuts and grain matching. Framing rarely needs more than 10-15 percent. See our waste factor glossary entry for benchmarks by trade.
Build a historical pricing log. Hardwood prices move quarterly with kiln capacity and import volumes; without recent data, your bid risks coming in 10 percent low.
When the truck arrives, count and measure a sample. Hardwood deliveries are often tallied by the supplier with a margin of error; verify before accepting the load.
Production field guide
The board foot formula is Thickness (inches) x Width (inches) x Length (feet) divided by 12. The result is the lumber volume in board feet. For example, a 2 x 6 board that is 10 feet long calculates as 2 x 6 x 10 / 12 = 10 board feet. If your length is in inches, divide the entire result by 144 instead of 12. One board foot equals 144 cubic inches of lumber, or roughly the volume of a 1 x 12 x 12 inch piece.
Separate plan workflow
This calculator solves one bounded formula from the inputs shown. BuildVision AI supports reviewed plan takeoff, complete-document CSV, and editable quote lines; the estimator owns pricing and final bid approval.