Board Foot Calculator
Calculate board feet of lumber.
Input
Result
What is a Board Foot Calculator?
The Board Foot Calculator helps you calculate board feet of lumber for woodworking and construction projects. Just enter your numbers and the tool does the rest — no manual math, no guesswork.
How to calculate Board Foot manually (the formula)
The specific formula depends on what you are calculating. The calculator applies the correct equation automatically, but understanding the formula helps you verify the results and adapt them to your own needs.
Example calculation
Enter your values into the calculator and it will produce an instant result. For a step-by-step walkthrough, try different inputs and observe how each one affects the outcome.
Common mistakes
- Using actual dimensions instead of nominal — Lumber is sold by nominal size. A 2×4 is calculated as 2 × 4, not 1.5 × 3.5.
- Forgetting to divide by 12 — The formula T × W × L gives cubic inches. Divide by 12 (or 144 for cubic feet) to get board feet.
- Not converting length to feet — Length must be in feet. If your board is 96 inches, convert to 8 ft first.
Frequently asked questions
What is a board foot?
A board foot is a unit of lumber volume equal to 1 ft × 1 ft × 1 in, or 144 cubic inches.
How do I calculate board feet?
Multiply thickness (in) × width (in) × length (ft) and divide by 12. Board feet = (T × W × L) ÷ 12.
What’s the difference between board foot and square foot?
Square foot measures area (length × width). Board foot measures volume (thickness × width × length).
How many board feet are in a 2×4?
An 8 ft long 2×4 has 5.33 board feet: (2 × 4 × 8) ÷ 12 = 5.33 bd ft.
How do I calculate lumber cost?
Multiply the total board feet by the price per board foot. Add waste (10–15%) for a safe estimate.
What is the nominal vs actual size in lumber?
A nominal 2×4 is actually 1½ in × 3½ in. Board foot calculations use nominal dimensions for simplicity.