About Lumber Calculations
Lumber is sold by the board foot (BF), which equals a piece of wood 1 inch thick, 12 inches wide, and 12 inches long (144 cubic inches). Understanding board feet calculations is essential for woodworking, construction, and purchasing lumber efficiently.
BF = (Thickness × Width × Length) / 144
Where dimensions are in inches, or:
BF = (T × W × L) / 12 (when length is in feet)
Nominal vs Actual Dimensions
Lumber is sold by nominal dimensions, which are larger than actual dimensions. A 2×4 is actually 1.5×3.5 inches. For board foot calculations, always use nominal dimensions as that is what you are paying for.
Common Lumber Sizes
- 2×4: Most common framing lumber
- 2×6: Floor joists, headers
- 2×8, 2×10, 2×12: Larger structural members
- 1×4, 1×6, 1×8: Trim and finish boards
- 4×4: Posts
How to Use
Enter the lumber dimensions (thickness, width, length) and quantity. The calculator computes total board feet and estimated cost based on your price per board foot.
Buying Tips
Always buy 10-15% extra for waste. Check for warping, splits, and knots. Kiln-dried lumber is more stable than air-dried. Hardwoods are priced per board foot while softwood framing lumber is typically priced per piece.
Common Wood Types and Costs
Pine: $3-6/BF, Oak: $6-10/BF, Maple: $5-9/BF, Walnut: $10-18/BF, Cherry: $7-12/BF. Prices vary by region, grade, and availability.