Board Footage Calculator
One formula, with the units kept explicit
For each row, board feet = thickness (in) × width (in) × length (ft) ÷ 12 × quantity. A 1-inch-thick, 12-inch-wide, 1-foot-long board is 1 BF. Three of these boards total 3 BF. At an entered price of $5 per BF, their estimated lumber cost is $15.
A second example uses two boards, each 6/4 inch thick, 8 inches wide, and 2 feet long. Each is 1.5 × 8 × 2 ÷ 12 = 2 BF; the pair totals 4 BF. At $4 per BF, that row costs $16. Add a separate 1 BF board priced at $5 per BF and the order totals 5 BF and $21 before other charges.
Compare billing dimensions and measured volume
The supplier's billing dimensions answer a different question from the dimensions you measure on a finished piece. This tool leaves that choice explicit: the main fields calculate billing footage and cost, while the optional comparison fields calculate the rectangular physical volume you enter.
For example, entered billing dimensions of 2 in × 4 in × 8 ft give about 5.333 BF. Separately measured dimensions of 1.5 in × 3.5 in × 8 ft give about 0.292 cubic feet, equivalent geometrically to 3.5 BF. The difference does not by itself mean a supplier overcharged; the billing method may intentionally use different dimensions.
When only some rows have measured dimensions, the comparison subtotal covers those same rows on both sides. It never compares a partial measured subtotal with the billing total for the entire order. The measured values do not change the cost estimate.
Keep supplier rules separate from the arithmetic
Supplier practices matter. For example, Woodworkers Source describes using a named thickness for its board-foot calculation even when the measured board is thinner. Its FAQ also specifies width and length rounding. Those are that supplier's instructions; this calculator does not silently apply them to every purchase.
Confirm the dimensions and tally rules on your quote, then enter those billing dimensions here. An unknown price stays unknown, while an explicit zero is treated as a zero price. The tool does not fetch lumber prices or infer the species, grade, moisture condition, or billing policy.
Use board feet for lumber volume
A linear foot measures length; a square foot measures area; a board foot measures volume using all three dimensions. This calculator handles rectangular lumber rows. It does not estimate the lumber yield of logs, plan cuts, or assess structural suitability.
Clear all returns to one blank row with quantity 1. Add or remove rows to match your list; incomplete dimensions clear the totals until the list is complete. Calculations run in your browser, and tool analytics do not include your dimensions, prices, or results.
Frequently asked questions
How do I calculate board footage?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. Multiply by the number of boards for the row total. If every dimension is in inches instead, divide their product by 144. This calculator expects thickness and width in inches and length in feet, as labeled.
What is one board foot?
One board foot represents a volume of 144 cubic inches: a piece 1 inch thick, 12 inches wide, and 12 inches long. It measures volume, not just length or surface area. Trade board footage can use billing dimensions that differ from the wood's physical dimensions.
Should I enter nominal or actual dimensions?
For a price estimate, enter the dimensions your supplier confirms it uses for billing. Do not assume a nominal size or an actual measurement always applies. Supplier tally, thickness, and rounding practices can differ. Use the optional measured-dimensions fields to compare physical volume without changing the billing calculation.
Can I enter 6/4 or mixed fractions?
Yes. Dimension fields accept decimals such as 1.5, simple fractions such as 6/4, and mixed numbers such as 1 1/2. All three mean 1.5. Enter the dimension in the unit shown next to the field. A lumber thickness name is not automatically a measurement of the finished board.
Can I add boards with different sizes and prices?
Yes. Add up to 20 rows. Each row has its own dimensions, quantity, and optional USD price per board foot. The tool adds unrounded row calculations, then rounds displayed values. If some prices are missing, it labels the known amount as a priced-rows subtotal rather than a complete order cost.
Does the estimate include waste, tax, or shipping?
No. It multiplies the entered billing board footage by the entered price per board foot. It does not automatically add waste, milling charges, tax, shipping, minimum order charges, or supplier tally rounding. Confirm those separately when comparing a supplier's quote.