A board foot calculator is an essential tool for woodworkers, lumber buyers, and construction professionals who need to accurately measure wood volume and estimate costs. Our calculator provides precise measurements based on lumber dimensions and quantity to help you plan projects and budget effectively.
A board foot is a unit of volume specifically used for measuring lumber in North America. It represents the equivalent of a piece of wood that is:
This standardized measurement allows for consistent pricing and planning across different wood types, sizes, and project requirements. Despite its name, a board foot is actually a measure of volume, not length or area.
Understanding board feet is crucial for several reasons:
The formula for calculating board feet is:
Board feet = (Length (feet) × Width (inches) × Thickness (inches)) ÷ 12
For multiple pieces of the same dimensions:
Total board feet = Board feet per piece × Number of pieces
This calculation standardizes wood measurements regardless of the actual dimensions of each piece.
Here are some examples to illustrate how the calculation works:
| Dimensions | Calculation | Board Feet |
|---|---|---|
| 1" × 12" × 8' | (8 × 12 × 1) ÷ 12 | 8 |
| 2" × 4" × 10' | (10 × 4 × 2) ÷ 12 | 6.67 |
| 3" × 6" × 12' | (12 × 6 × 3) ÷ 12 | 18 |
| 4" × 8" × 16' | (16 × 8 × 4) ÷ 12 | 42.67 |
| 1.5" × 3.5" × 8' | (8 × 3.5 × 1.5) ÷ 12 | 3.5 |
Note that the actual dimensions of dimensional lumber may differ from their nominal sizes (e.g., a "2×4" actually measures approximately 1.5" × 3.5"), so it's important to use the actual dimensions for accurate calculations.
When purchasing dimensional lumber, be aware that the stated dimensions (like "2×4") are nominal sizes, not actual measurements. For the most accurate board foot calculations, always use the actual dimensions:
| Nominal Size | Typical Actual Size |
|---|---|
| 1×4 | 0.75" × 3.5" |
| 1×6 | 0.75" × 5.5" |
| 1×8 | 0.75" × 7.25" |
| 2×4 | 1.5" × 3.5" |
| 2×6 | 1.5" × 5.5" |
| 2×8 | 1.5" × 7.25" |
| 2×10 | 1.5" × 9.25" |
| 2×12 | 1.5" × 11.25" |
| 4×4 | 3.5" × 3.5" |
Rough lumber (unplaned) will have dimensions closer to the nominal size, while surfaced lumber (S4S - surfaced four sides) will have the reduced dimensions shown above. The calculator works for both types, but you must input the correct dimensions.
Lumber prices fluctuate based on:
To estimate total cost, multiply the total board feet by the price per board foot:
Total cost = Total board feet × Price per board foot
Exotic and specialty hardwoods are almost always priced by the board foot. These higher-value woods can range from:
Knowing the precise board footage is especially important when working with these premium materials.
Our board foot calculator handles various input scenarios:
The calculator automatically converts inches to feet where appropriate and handles fractional measurements to three decimal places for precision.
For the most accurate results, measure or confirm the actual dimensions of your lumber rather than relying on nominal sizes.
This calculator uses the standard board foot formula recognized throughout the North American lumber industry. For specific pricing in your area, consult with local lumber suppliers.