Board Foot Calculator
Calculate board feet for lumber pricing and estimation. Supports nominal lumber sizes and custom dimensions.
Board Foot Calculator
Calculate board feet for lumber pricing and estimation
Or enter custom dimensions:
Nominal vs Actual Sizes
Lumber is sold by nominal size (e.g., 2×4), but actual dimensions are smaller after drying and planing. A 2×4 is actually 1.5" × 3.5". This calculator uses actual dimensions for accurate board foot calculations.
Formula
Board Feet = (Thickness × Width × Length) / 12Where thickness and width are in inches, and length is in feet. One board foot equals 144 cubic inches (1 ft × 1 ft × 1 in).
Nominal vs Actual Lumber Sizes (8-foot length)
| Nominal Size | Actual Size | Board Feet (8') |
|---|---|---|
| 1×2 | 0.75" × 1.5" | 1.00 BF |
| 1×4 | 0.75" × 3.5" | 2.33 BF |
| 1×6 | 0.75" × 5.5" | 3.67 BF |
| 1×8 | 0.75" × 7.25" | 4.83 BF |
| 1×12 | 0.75" × 11.25" | 7.50 BF |
| 2×4 | 1.5" × 3.5" | 3.50 BF |
| 2×6 | 1.5" × 5.5" | 5.50 BF |
| 2×8 | 1.5" × 7.25" | 7.25 BF |
| 2×10 | 1.5" × 9.25" | 9.25 BF |
| 2×12 | 1.5" × 11.25" | 11.25 BF |
| 4×4 | 3.5" × 3.5" | 8.17 BF |
Understanding Board Feet
What is a Board Foot?
A board foot (BF) is the standard unit of measurement for lumber volume in the United States. One board foot equals 144 cubic inches—equivalent to a piece of wood 12 inches long, 12 inches wide, and 1 inch thick.
The Formula
Where thickness and width are in inches, and length is in feet.
Why Use Board Feet?
Board feet provide a standardized way to price lumber regardless of dimensions. Hardwood lumber is typically sold by the board foot, while softwood (like construction lumber) is often sold by the linear foot or piece.
How to Use
- 1Select lumber size — Choose a nominal lumber size (like 2x4 or 2x6) from the dropdown, or enter custom dimensions.
- 2Enter length — Select a common length or enter a custom length in feet.
- 3Set quantity — Enter the number of pieces you need.
- 4Add price (optional) — Enter the price per board foot to calculate total cost.
- 5View results — See board feet per piece, total board feet, and total price.
Frequently Asked Questions
What is a board foot?
A board foot is a unit of volume for lumber equal to 144 cubic inches, or the volume of a board 1 foot long, 1 foot wide, and 1 inch thick. It's the standard unit for pricing hardwood lumber in the United States.
How do I calculate board feet?
Board feet = (Thickness × Width × Length) / 12, where thickness and width are in inches and length is in feet. For example, a 2" × 6" × 8' board = (2 × 6 × 8) / 12 = 8 board feet.
What's the difference between nominal and actual lumber sizes?
Nominal size is the name used to sell lumber (like 2x4), while actual size is the true dimension after drying and planing. A nominal 2x4 is actually 1.5" × 3.5". This calculator uses actual dimensions for accurate calculations.
Why is lumber sold by board feet?
Board feet provide a standardized way to price lumber regardless of dimensions. This allows fair pricing comparison between different sizes and makes it easier to estimate costs for projects requiring various lumber sizes.
How much waste should I add to my lumber estimate?
A common rule is to add 10-15% for waste due to cutting, defects, and mistakes. For complex projects with many cuts, consider adding up to 20%.