siteworkcalcChoose a dimension basis
For an order, ask which thickness and width the supplier uses for pricing. For physical volume, enter measured sizes. A trade name such as “2×4” is not a measurement of the finished board.
WOOD & OUTDOOR / TOOL 05
Board Foot Calculator.
Different board sizes. One clear lumber tally.
Calculate board feet, extra material and a price for the whole list.
01 / YOUR LUMBER
Build your board list
02 / YOUR TALLY
Every size accounted for
Add your board dimensions and quantities to see a row-by-row breakdown.
Order board feet, including allowance
BF
A tally you can check at the lumberyard
Add each size once
Enter the thickness, width, length and count for each group. Different sizes get separate rows. The result shows board feet per piece and a subtotal for each row.
Price a consistent tally
Optional extra material increases the total volume once. A single price per BF applies to the whole order. Separate different species or price grades into their own calculations.
THE CALCULATION
Volume first, cost second
BF per piece = thickness (in) × width (in) × length (ft) ÷ 12Total BF = sum of each row’s BF × quantityOrder BF = total BF × (1 + extra % ÷ 100)For metric input, convert thickness and width from millimeters to meters; multiply by length in meters and divide by 0.002359737216 to obtain BF per piece. Cost = order BF × price per BF. Keep full precision until display.
Two sizes, one tally
Three 1 × 6 in boards, each 8 ft long: 4 BF each, or 12 BF. Two 2 × 8 in boards, each 10 ft long: 13.3333 BF each, or 26.6667 BF.
Combined: 38.6667 BF. With an example 10% extra, the order is 42.5333 BF. At an illustrative $5/BF, material cost is $212.67. No whole-board purchase rounding is applied.
Before buying lumber
Nominal and actual board feet
Using 2 × 4 in and an 8 ft length gives 5.3333 BF. Entering measured dimensions of 1.5 × 3.5 in and the same length gives 3.5 BF. These answer different questions: label your basis and confirm the supplier’s tally before comparing prices.
What does 4/4 lumber mean?
Quarter notation describes thickness in quarter inches: 4/4 = 1 in, 5/4 = 1.25 in, 6/4 = 1.5 in and 8/4 = 2 in. Surfaced stock may measure less. Use the agreed pricing thickness when checking a quote.
Estimating roof framing lumber?
Use the Roof Pitch Calculator to understand the slope and geometric line length. Return here with verified stock dimensions, purchase lengths and quantities. Neither tool selects a structural member size or a cut layout.
FIELD NOTES
Common questions
What is a board foot?
One board foot is 144 cubic inches: a piece 1 in thick, 12 in wide and 12 in long. It is 1/12 ft³, or exactly 0.002359737216 m³. BF and bd ft are common abbreviations; this tool uses BF.
Is a board foot the same as a square or linear foot?
No. Board feet measure volume, square feet measure area and linear feet measure length. At a known thickness in inches, board feet equal face area in square feet multiplied by that thickness.
Does this reproduce an NHLA grading tally?
No. This tool multiplies the entered dimensions without rounding thickness or length to grading increments. Suppliers may apply different tally conventions. Confirm those rules and enter the appropriate dimensions when estimating a purchase.
Can I estimate logs with this calculator?
This is for rectangular lumber. Estimating recoverable lumber from a log requires a log-scaling rule such as Doyle, Scribner or International, and is a different calculation.
METHOD & REFERENCES
Sources and assumptions
Reviewed October 21, 2026. Rectangular volume using the dimensions entered. No default lumber price, allowance, nominal-size conversion or grading-rule rounding.