Lumber Calculator
Calculate board feet, costs, and materials for framing projects
Board Feet Formula & Tips
Board Feet = (Width × Height × Length) ÷ 12
- Width and height are nominal dimensions (2x4, 2x6, etc.)
- Actual dimensions are smaller than nominal (2x4 is actually 1.5" × 3.5")
- Standard lumber lengths: 8', 10', 12', 14', 16', 20'
- Prices vary by species, grade, and market conditions
- Add 5-10% extra for cuts and waste
How to Use the Lumber Calculator
- Select lumber size: Choose from common dimensions like 2×4, 2×6, 2×8, etc.
- Choose length: Select from standard lengths (8', 10', 12', 14', 16', 20').
- Enter quantity: Input the number of pieces you need.
- Set custom price: Optionally enter your local lumber price per board foot.
- Review calculations: Get total board feet, linear feet, weight, and estimated cost.
Understanding Board Feet
Board Feet Formula
Board Feet = (Width × Height × Length) ÷ 12
Where width and height are in inches, length is in feet, and the result is in board feet.
Example Calculation
A 2×6×10 board:
Width: 2 inches
Height: 6 inches
Length: 10 feet
(2 × 6 × 10) ÷ 12 = 10 board feet
Why Use Board Feet?
- • Standard lumber pricing unit
- • Allows comparison across different sizes
- • Simplifies cost calculations
- • Industry standard measurement
Standard Lumber Sizes & Uses
| Nominal Size | Actual Size | Common Uses | Typical Price/BF |
|---|---|---|---|
| 2×4 | 1.5" × 3.5" | Framing, studs, plates | $0.60-$0.80 |
| 2×6 | 1.5" × 5.5" | Floor joists, rafters | $0.70-$0.90 |
| 2×8 | 1.5" × 7.25" | Floor joists, beams | $0.80-$1.00 |
| 2×10 | 1.5" × 9.25" | Beams, headers, joists | $0.90-$1.20 |
| 2×12 | 1.5" × 11.25" | Large beams, long spans | $1.00-$1.40 |
| 4×4 | 3.5" × 3.5" | Posts, deck construction | $1.20-$1.50 |
Lumber Grades & Quality
Structural Grades
- Select Structural: Highest grade, minimal defects
- No. 1 & Better: Good strength, some small knots
- No. 2: Most common, good for framing
- No. 3: Utility grade, lower strength
Wood Species
- Douglas Fir: Strong, straight grain, popular
- Southern Pine: Dense, strong, pressure-treated
- Hem-Fir: Light, easy to work with
- SPF: Spruce-Pine-Fir, economical choice
Lumber Planning & Buying Tips
Before You Buy
- • Check lumber for warping, splits, and knots
- • Buy 10-15% extra for waste and mistakes
- • Consider moisture content for your project
- • Compare prices at different suppliers
- • Check for treated lumber where needed
Storage & Handling
- • Store lumber flat and off the ground
- • Keep lumber dry to prevent warping
- • Support long boards at multiple points
- • Separate layers with stickers for air flow
- • Use lumber within a reasonable time frame
Common Framing Requirements
Wall Framing (per linear foot)
- • 2×4 studs @ 16" OC: ~1 stud per foot + plates
- • Top and bottom plates: 2 pieces per linear foot
- • Headers: Size depends on opening span
- • Cripples and blocking as needed
Floor Framing
- • Joist size depends on span and load
- • 2×6 joists: up to 10' spans
- • 2×8 joists: up to 13' spans
- • 2×10 joists: up to 16' spans
Related Construction Calculators
Frequently Asked Questions
What's the difference between nominal and actual lumber sizes?
Nominal sizes (2×4) are the rough-sawn dimensions. Actual sizes (1.5"×3.5") are after planing and drying. Always use actual dimensions for precise calculations.
How much does lumber weigh?
Dry lumber weighs about 2.5 pounds per board foot for most species. Green (wet) lumber can weigh significantly more.
Should I buy kiln-dried or air-dried lumber?
Kiln-dried lumber has lower moisture content and is more stable. It's preferred for indoor projects and precision work.
What grade lumber should I use for framing?
No. 2 grade or better is typically used for structural framing. Check local building codes for specific requirements.