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Lumber Calculator
Calculate board feet, linear footage, weight, and cost for any lumber dimension and species
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Lumber Calculator
How to Calculate Board Feet of Lumber
Board feet is the standard unit for measuring lumber volume in the United States. It is calculated using nominal dimensions — the traditional names like 2×4 or 2×6 — not the actual surfaced dimensions. To find board feet, multiply thickness in inches by width in inches by length in feet, then divide by 12.
Board Foot Formula
BF per Piece = (Thickness" × Width" × Length ft) ÷ 12
Total BF = BF per Piece × Number of Pieces
Total Linear Ft = Length per Piece × Number of Pieces
Cost = Total BF × Price per BF
BF per Piece = (Thickness" × Width" × Length ft) ÷ 12
Total BF = BF per Piece × Number of Pieces
Total Linear Ft = Length per Piece × Number of Pieces
Cost = Total BF × Price per BF
Lumber Species Comparison
| Species | Cost/BF | Weight/BF | Best Use |
|---|---|---|---|
| SPF / Douglas Fir | ~$0.50 | ~2.5 lbs | Interior framing, general construction |
| Southern Yellow Pine | ~$0.55 | ~2.7 lbs | Floors, heavy-load framing |
| Cedar | ~$2.50 | ~1.8 lbs | Outdoor siding, fencing, closets |
| Redwood | ~$4.00 | ~1.9 lbs | Decks, outdoor structures |
| Pressure Treated | ~$0.70 | ~3.0 lbs | Ground contact, decks, sill plates |
Lumber Buying Tips
- Always add 10–15% to your board foot calculation to account for defects, cuts, and waste
- Inspect each board for crowns, cups, twists, and large knots before purchasing
- Stack lumber flat on a level surface and sticker (separate) boards with spacers for good airflow if storing on site
- For ground contact or within 6 inches of soil, use pressure-treated lumber rated UC4A or higher
- Kiln-dried (KD) lumber is more dimensionally stable and lighter to handle than green lumber
? Frequently Asked Questions
What is a board foot of lumber?
A board foot (BF) is a unit of lumber volume equal to 1 inch thick × 12 inches wide × 12 inches long (144 cubic inches). It is calculated as: (Thickness" × Width" × Length ft) ÷ 12. A 2×4 that is 8 feet long contains 5.33 board feet.
What is the difference between nominal and actual lumber dimensions?
Nominal dimensions are the traditional names (2×4, 2×6, etc.). Actual dimensions are smaller because the lumber is dried and surfaced (planed) after cutting. A nominal 2×4 measures 1.5" × 3.5" actual. A 2×6 is 1.5" × 5.5" actual. Board foot calculations use the nominal (larger) dimensions.
What is the best lumber for framing?
SPF (Spruce-Pine-Fir) and Douglas Fir are the standard choices for interior framing — strong, light, and widely available. Southern Yellow Pine (SYP) is denser and stronger, preferred in the Southeast. For outdoor use, pressure-treated lumber (PT) is required. Cedar and Redwood are premium choices for exposed outdoor applications.
How much does lumber cost per board foot?
Prices vary by region, species, and market conditions. SPF typically runs $0.40–0.70/BF at current retail. Southern Yellow Pine is $0.45–0.70/BF. Cedar runs $2–3/BF. Redwood is $3.50–5/BF. Pressure-treated lumber is $0.55–0.90/BF depending on retention level.
How do I calculate the weight of lumber?
Lumber weight depends on species and moisture content. Green (wet) lumber weighs significantly more than kiln-dried. Approximate dry weights: SPF/Douglas Fir 2.5 lbs/BF, Southern Yellow Pine 2.7 lbs/BF, Cedar 1.8 lbs/BF, Redwood 1.9 lbs/BF. A unit of 1,000 BF of dry SPF weighs about 2,500 lbs.
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💡 Pro Tips
Always add 10% extra to material estimates to account for waste, cuts, and mistakes.