You've got a stack of lumber in various sizes (2×4s, 2×6s, 2×10s), and you need to know: how many board feet is this, and what does it cost?
Board feet is the lumber industry's standard measurement. One board foot is 1 inch thick × 12 inches wide × 12 inches long (or any equivalent volume: 144 cubic inches). It's different from linear feet (which ignores thickness and width). Calculating board feet correctly helps you compare lumber prices fairly, order the right amount, and budget accurately. Our board foot calculator converts any lumber dimensions into board feet instantly.
What This Calculator Does
This tool converts lumber dimensions into board feet. You input the thickness (in inches), width (in inches), and length (in feet) of your lumber, and the calculator shows total board feet. For multiple pieces, input quantity and dimensions once, and we multiply. The result is what you'd tell a lumber supplier when ordering or what you'd use to compare price quotes across different dimensions (a $5-per-board-foot price is fair regardless of whether it's 2×4 or 2×12 lumber).
How to Use This Calculator
Step 1: Measure or identify the thickness of your lumber in inches. Nominal (labeled) thickness is slightly different from actual: a "2×4" is actually 1.5" thick × 3.5" wide. Use actual thickness, not nominal.
Step 2: Measure the width in inches. A "2×4" is 3.5" wide; a "2×6" is 5.5" wide; a "2×10" is 9.25" wide. Again, use actual width, not nominal.
Step 3: Measure or note the length in feet. This is usually straightforward: a 10-foot board is 10 feet long.
Step 4: If you have multiple pieces of the same size, input the quantity and we multiply.
Step 5: The calculator shows total board feet. Use this number for ordering, pricing comparisons, or project budgeting.
The Formula Behind the Math
Board feet calculation is straightforward:
Board Feet = (Thickness inches × Width inches × Length feet) ÷ 12
Let's work through examples of common lumber sizes:
A single 2×4 that's 10 feet long:
A single 2×10 that's 16 feet long (joist):
Ten 2×6 boards, 12 feet each (deck boards):
Our calculator does this instantly for any combination of sizes and quantities.
Deck Building Project (Mixed Sizes)
A deck project requires various lumber sizes. Let's calculate a typical scenario:
At $0.60–$1.00 per board foot (depending on wood species and quality), this deck project would cost $750–$1,250 in lumber alone.
Fence Project (Posts and Boards)
A 200-linear-foot fence with 6-foot spacing:
At $0.50–$0.80 per board foot for pressure-treated lumber, this fence costs $265–$425 in material.
Cabinet or Furniture Project (Fine Hardwood)
A custom cabinet made from hardwood (oak, walnut, etc.):
At $8–$15 per board foot for premium hardwood, this cabinet uses $1,135–$2,130 in lumber, not including hardware or finishing.
Tips and Things to Watch Out For
Nominal vs. actual dimensions matter-always use actual dimensions. A "2×4" is actually 1.5 × 3.5 inches. A "1×12" is actually 0.75 × 11.25 inches. Nominal is the label; actual is what you use in calculations. Lumber yards have published charts showing actual dimensions for all sizes.
Green (wet) lumber shrinks as it dries-account for this in precision work. Freshly cut lumber has high moisture content and will shrink 5–10% as it dries. For rough construction (framing), this is acceptable. For furniture or trim where fit matters, let lumber acclimate to room humidity for 7–14 days before final measurement.
Pressure-treated lumber costs roughly 20–30% more than untreated softwood. For any ground-contact use (fence posts, deck footings), pressure-treated is mandatory. Untreated outdoor lumber rots within 3–5 years. Budget for the premium upfront.
Always order 10–15% more material than your calculation to account for waste, cuts, breakage, and measurement errors. Lumber is cut to length and angle on-site. Some boards arrive warped, cracked, or damaged. Order the calculated amount plus 10–15% extra.
Hardwood lumber is sold rough or planed; planed lumber costs more and is slightly smaller. Rough 1×12 is actually 1" × 12". Planed (S4S, "surfaced four sides") is closer to 0.75" × 11.25". Confirm which you're buying-affects thickness in calculations.
Compare prices per board foot, not per board. A 2×4×8 might be $5, but that's 2.67 board feet = $1.87 per board foot. A 2×10×12 might be $12, but that's 18.75 board feet = $0.64 per board foot. Price per board foot lets you compare apples to apples across sizes.
Frequently Asked Questions
How many board feet is a 2×4×8?
A 2×4×8: actual dimensions 1.5" × 3.5" × 8 feet = (1.5 × 3.5 × 8) ÷ 12 = 42 ÷ 12 = 3.5 board feet.
How many board feet is a 2×10×16?
A 2×10×16: actual dimensions 1.5" × 9.25" × 16 feet = (1.5 × 9.25 × 16) ÷ 12 = 222 ÷ 12 = 18.5 board feet.
What's the difference between board feet and linear feet?
Linear feet is just length (ignores thickness and width). A 2×4×8 is 8 linear feet but 3.5 board feet. Board feet accounts for thickness and width, so it reflects actual lumber volume. Lumber is priced per board foot; linear feet is useful for flooring or trim but not lumber.
How many board feet in a cord of wood?
A cord is 128 cubic feet (4 × 4 × 8 feet stacked). One board foot is 144 cubic inches. A cord ≈ 1,280 board feet. But this varies; a cord of firewood isn't the same density as dimensioned lumber. Usually, lumber is sold by the board foot or in specific quantities, not cords.
How do I calculate board feet for irregular pieces?
For rough lumber (slabs, live-edge), measure the thickest and widest points, and calculate as if it were rectangular. Or have your lumber supplier measure and calculate. Some material is sold by weight or rough estimate rather than precise board feet.
Do I need to account for saw kerf (blade thickness) in my calculations?
Saw kerf (the small amount of material lost to the saw blade during cutting) is typically 0.125–0.25 inches. For rough estimates, it's negligible. For precision work (cabinet making, trim), add 0.25 inches to the rip dimension (width). It's usually too small to matter for construction framing.
How much does lumber cost per board foot?
Softwood (pine, fir): $0.50–$1.50 per board foot. Pressure-treated softwood: $0.80–$2.50 per board foot. Oak hardwood: $4–$8 per board foot. Walnut or cherry: $8–$20 per board foot. Prices vary by region, species, grade, and market conditions. Get quotes from 2–3 suppliers.
What's the difference between lumber grades?
Grade affects price and appearance. Construction grade (common, lower cost): knots and defects allowed, fine for framing. Select grade: fewer defects, better appearance, higher cost. Clear grade: no knots, premium, most expensive. For visible surfaces (trim, furniture), select or clear. For hidden framing, construction grade is fine.
Related Calculators
Use the deck calculator, fence calculator, and other construction project calculators to estimate lumber needs. The material cost estimator helps budget total project cost across lumber, hardware, and labor.