Board Foot Calculator – Estimate Lumber Volume & Cost
Calculate board feet for any lumber size. Enter thickness, width, and length to get board feet, total for multiple pieces, and estimated cost.
Board Foot Calculator Formula
Board Feet = (Thickness (in) × Width (in) × Length (ft)) / 12
How to Calculate Board Foot
- 1. Measure the thickness of the board in inches (use nominal dimensions, e.g. 2 for a 2×4)
- 2. Measure the width in inches (e.g. 4 for a 2×4)
- 3. Measure the length in feet
- 4. Calculate: Board Feet = (Thickness × Width × Length) / 12
- 5. For multiple boards: Total BF = Board Feet × Quantity
- 6. For cost: Cost = Total Board Feet × Price per BF
Example Calculation
Let's say you're calculating board feet for ten 2×6 boards that are 10 feet long.
- thickness: 2
- width: 6
- length: 10
- quantity: 10
Each board = 10.00 bf, total = 100.00 board feet. At $4.50/bf, cost = $450.00. Equivalent to about 13 standard 2×4×12 boards.
Tips
- Use nominal dimensions (e.g., 2×4, not the actual 1.5×3.5) for board foot calculations
- A standard 2×4×8 = 5.33 board feet; a 2×4×12 = 8 board feet
- Board foot price varies by species: pine ≈ $2–4/bf, oak ≈ $4–8/bf, exotic woods ≈ $10+/bf
- Always buy 10–15% extra lumber to account for waste, defects, and cutting errors
Frequently Asked Questions
What is a board foot?
A board foot is a unit of lumber volume equal to 144 cubic inches — a board that is 12 inches wide, 1 inch thick, and 12 inches long (or any combination with the same volume). The formula is: BF = (Thickness (in) × Width (in) × Length (ft)) / 12.
How many board feet in a 2×4×8?
A 2×4×8 board contains 5.33 board feet: (2 × 4 × 8) / 12 = 5.33 bf. Note this uses nominal dimensions (the actual size of a 2×4 is about 1.5×3.5 inches, but board feet always uses nominal size).
How do I calculate how much lumber I need?
List all the boards you need by size (thickness, width, length) and quantity. Calculate board feet for each size using (T × W × L) / 12, multiply by quantity, and sum all sizes. Add 10–15% for waste.