How to Calculate Board Feet of Lumber
A board foot (abbreviated bd.ft or BF) is the standard volume unit for pricing and measuring lumber in North America. It equals the volume of a board that is exactly 1 inch thick × 12 inches wide × 1 foot (12 inches) long — equivalent to 144 cubic inches or 1/12 of a cubic foot. Because it captures volume — not just surface area — it accounts for thickness, making it the accurate way to compare and purchase hardwood.
- BF = Board feet (volume result)
- T = Thickness in inches (nominal)
- W = Width in inches (nominal)
- L = Length in feet
- ÷12 = Converts in² × ft to board feet (since 1 bd.ft = 12 in² × 1 ft)
An equivalent formula when all three dimensions are in inches is BF = (T × W × L) ÷ 144, since 1 board foot = 144 cubic inches. Both formulas produce identical results — choose whichever matches your input units. For multiple pieces, multiply the per-board result by the quantity: Total BF = BF × Qty.
To estimate cost, multiply total board feet by the price per board foot: Cost = Total BF × Price/BF. Hardwood prices are almost universally quoted in board feet, while softwood construction lumber is often sold by the linear foot — always verify which unit your supplier uses before estimating project costs.
| Nominal Size | T × W (in) | BF per Lin. Ft | 10 ft board | Typical Use |
|---|---|---|---|---|
| 1×2 | 1″ × 2″ | 0.167 BF | 1.67 BF | Furring, trim |
| 1×4 | 1″ × 4″ | 0.333 BF | 3.33 BF | Shelving, fascia |
| 1×6 | 1″ × 6″ | 0.500 BF | 5.00 BF | Paneling, fence boards |
| 1×8 | 1″ × 8″ | 0.667 BF | 6.67 BF | Siding, shelving |
| 1×12 | 1″ × 12″ | 1.000 BF | 10.00 BF | Shelving, tabletops |
| 2×4 | 2″ × 4″ | 0.667 BF | 6.67 BF | Framing, studs |
| 2×6 | 2″ × 6″ | 1.000 BF | 10.00 BF | Joists, rafters |
| 2×8 | 2″ × 8″ | 1.333 BF | 13.33 BF | Headers, floor joists |
| 2×10 | 2″ × 10″ | 1.667 BF | 16.67 BF | Floor joists, beams |
| 2×12 | 2″ × 12″ | 2.000 BF | 20.00 BF | Stair stringers, beams |
| 4×4 | 4″ × 4″ | 1.333 BF | 13.33 BF | Posts, columns |
| 4×6 | 4″ × 6″ | 2.000 BF | 20.00 BF | Beams, landscape timbers |
Frequently Asked Questions
What is the difference between a board foot and a linear foot?
A linear foot measures only the length of a board — a 1×6 and a 2×12 are both "8 linear feet" if they are 8 feet long, regardless of size. A board foot measures volume (T × W × L ÷ 12), so that same 2×12 at 8 feet contains 16 board feet while the 1×6 contains only 4 board feet. Hardwood lumber and rough-sawn timber are priced per board foot because it reflects the actual amount of wood you receive. Softwood dimensional lumber sold at home centers is typically priced per linear foot or per piece, so always confirm the pricing unit with your supplier.
Do I use nominal or actual dimensions in the board foot formula?
By industry convention, nominal dimensions are used when calculating board feet for pricing purposes — not the actual (dressed/surfaced) dimensions. A surfaced 2×4 actually measures approximately 1.5″ × 3.5″, but you calculate and pay for it as if it were a full 2×4 (2″ × 4″). This is standard practice codified by the National Hardwood Lumber Association (NHLA) and widely followed across the industry. When measuring rough-sawn lumber you've personally milled, use the actual measured dimensions since no material has been removed.
How much does lumber cost per board foot in 2025–2026?
Common hardwood prices range from approximately $3–$8 per board foot for domestic species (oak, maple, poplar, ash) and $8–$20+ per board foot for premium or exotic species (black walnut, cherry, mahogany, teak). Softwood construction lumber (pine, fir, spruce) is typically cheaper and ranges from $0.50–$2.50 per board foot equivalent, though it is often sold by the piece. Prices vary significantly by region, grade (FAS, Select, #1 Common), moisture content (kiln-dried costs more than green), and market conditions. Always get a current quote from your local supplier for accurate project budgeting.