Board Foot Calculator Formula
Understand the math behind the board foot calculator. Each variable explained with a worked example.
Formulas Used
Board Feet (per board)
bf_per_board = thickness * width * length_ft / 12Total Board Feet
total_bf = thickness * width * length_ft / 12 * quantityVariables
| Variable | Description | Default |
|---|---|---|
thickness | Thickness(inches) | 2 |
width | Width(inches) | 8 |
length_ft | Length(feet) | 10 |
quantity | Number of Boards | 1 |
How It Works
How to Calculate Board Feet
Formula
Board Feet = (Thickness in inches × Width in inches × Length in feet) / 12
One board foot equals 144 cubic inches of wood. This is the standard measurement for buying and selling hardwood lumber. Thickness and width are in inches, length is in feet.
Worked Example
A single board 2 inches thick, 8 inches wide, 10 feet long.
- 01Board feet = (2 × 8 × 10) / 12 = 160 / 12 = 13.33 BF
Frequently Asked Questions
What is a board foot?
A board foot is a unit of lumber volume: 1 inch thick × 12 inches wide × 12 inches long, equaling 144 cubic inches. It is used primarily for pricing hardwood lumber.
Do I use nominal or actual dimensions?
For hardwood lumber, use the actual rough dimensions. For softwood dimensional lumber (2×4, 2×6, etc.), nominal dimensions are traditionally used for board foot calculations.
How do I convert board feet to square feet?
For 1-inch-thick lumber: board feet = square feet. For 2-inch-thick lumber: board feet = 2 × square feet. Divide board feet by the thickness in inches to get square feet of coverage.
Learn More
Guide
Understanding Lumber Dimensions: Nominal vs. Actual Sizes
Learn the difference between nominal and actual lumber dimensions. Covers common framing sizes, board feet calculations, hardwood grading, and how to choose the right lumber for your project.
Ready to run the numbers?
Open Board Foot Calculator