Lumber Board Foot
Calculate board feet for lumber pricing and quantity estimates. Convert lumber dimensions to board feet with cost calculator.
Formula
Board Feet = (T x W x L) / 12
Multiply thickness (inches) x width (inches) x length (feet), then divide by 12 to get board feet.
Worked Examples
Example 1: Calculate Board Feet
Problem:10 pieces of 2×6×12 lumber.
Solution:Per board: (2 × 6 × 12) / 12 = 12 board feet Total: 12 BF × 10 = 120 board feet At $0.85/BF: Cost = 120 × $0.85 = $102
Result:120 board feet, $102 total
Example 2: Compare Lumber Options
Problem:Need 100 BF. Compare: 2×6×10 at $12/piece vs 2×8×12 at $20/piece.
Solution:2×6×10: BF = (2×6×10)/12 = 10 BF/piece Pieces: 100/10 = 10 pieces Cost: 10 × $12 = $120 2×8×12: BF = (2×8×12)/12 = 16 BF/piece Pieces: 100/16 = 6.25 → 7 pieces Cost: 7 × $20 = $140 (7 pieces = 112 BF)
Result:2×6×10 is cheaper: $120 vs $140
Example 3: Deck Framing Estimate
Problem:Deck needs 20 joists (2×8×12) + 2 beams (2×10×16). Calculate total BF.
Solution:Joists: (2×8×12)/12 = 16 BF each 20 × 16 = 320 BF Beams: (2×10×16)/12 = 26.67 BF each 2 × 26.67 = 53 BF Total: 320 + 53 = 373 board feet
Result:373 board feet for framing
Frequently Asked Questions
What is a board foot?
A board foot is 144 cubic inches of lumber (1" × 12" × 12" or any combination equaling 144 cu in). It's the standard unit for pricing and measuring lumber. A 2×6×10 contains 10 board feet: (2 × 6 × 120) / 144 = 10 BF.
How do I calculate board feet?
Formula: (Thickness in inches × Width in inches × Length in feet) / 12. Example: 2×4×8 board: (2 × 4 × 8) / 12 = 5.33 board feet. Multiply by quantity for total. Note: nominal vs actual dimensions don't affect board foot calculation - use nominal.
What are nominal vs actual lumber dimensions?
Nominal (name): 2×4, 2×6, etc. Actual (real): 1.5"×3.5", 1.5"×5.5". Lumber is planed/surfaced after initial cut, reducing dimensions. Board feet are calculated using nominal dimensions, but building calculations use actual dimensions.
How much does lumber cost per board foot?
Varies widely by species, grade, and market: Framing lumber (SPF): $0.50-2.00/BF. Hardwoods (oak, maple): $3-12/BF. Premium (walnut, cherry): $8-20/BF. Prices fluctuate with market conditions. Always check current local pricing.
What lumber sizes are standard?
Thickness: 1×, 2×, 4×, 6× (actual: ¾", 1.5", 3.5", 5.5"). Width: 2, 4, 6, 8, 10, 12 inches (actual: 1.5", 3.5", 5.5", 7.25", 9.25", 11.25"). Length: 8, 10, 12, 14, 16 feet common. Longer lengths available but more expensive.
How do I estimate framing lumber?
Studs: wall length / spacing (16" or 24") + extra for corners, openings. Plates: 2× wall length for top/bottom. Joists: room span / spacing + 1. Headers: measure each opening. Add 10-15% waste. Board foot calculation helps compare pricing.
What's the difference between dimensional lumber and boards?
Dimensional lumber: 2× and thicker (2×4, 2×6, 2×8, etc.), used for framing. Boards: less than 2" thick (1×4, 1×6, 1×8), used for sheathing, trim, shelving. Both measured in board feet, but applications and pricing differ.
Should I buy lumber by board foot or piece?
Retail (Home Depot, Lowe's): priced per piece. Lumber yards: often priced per board foot or per thousand board feet (MBF). Board foot pricing allows comparing different sizes fairly. Buying in quantity often gets discounts - ask for contractor pricing.
What is MBF?
MBF = thousand board feet (M is Roman numeral for 1,000). Wholesale lumber pricing uses MBF. Example: $500/MBF = $0.50 per board foot. Large construction projects order in MBF quantities. Helps quote/compare large material quantities.
How do I account for lumber waste?
Standard waste factors: Framing: 10-15% (cuts, damage, mistakes). Trim/finish: 5-10% (more precision cuts). Decking: 10-15% (end cuts, warped boards). Complex layouts: 15-20%. Better to have extra than make additional trips. Save cutoffs for blocking.
Background & Theory
Board feet measure lumber volume for pricing and quantity calculations. Understanding board feet helps estimate costs and compare options.
Board Foot Formula:
Board Feet = (Thickness × Width × Length) / 12
(Thickness and width in inches, length in feet)
Common Lumber Board Feet:
| Size | 8 ft | 10 ft | 12 ft | 16 ft |
|---|---|---|---|---|
| 1×6 | 4 BF | 5 BF | 6 BF | 8 BF |
| 2×4 | 5.33 | 6.67 | 8 | 10.67 |
| 2×6 | 8 | 10 | 12 | 16 |
| 2×8 | 10.67 | 13.33 | 16 | 21.33 |
| 2×10 | 13.33 | 16.67 | 20 | 26.67 |
Pricing:
Cost = Board Feet × Price per BF
Waste Factor:
Add 10-15% for cuts and waste