Board Foot Calculator
Calculate total lumber board footage (BF), wood volume, and estimated purchase cost for woodworking and framing projects.
Board Dimensions & Quantity
Lumber Volume & Cost
How to Calculate Board Feet (BF)
A board foot is a specialized volumetric unit of measure for rough and finished lumber in the United States and Canada. One board foot represents the volume of a 1-foot long board that is 1 foot wide and 1 inch thick ($144\text{ in}^3$).
For deeper analysis and related planning, you can also explore our Concrete Calculator and Paint Calculator.
$$\text{Board Feet (when Length is in Feet)} = \frac{\text{Thickness (in)} \times \text{Width (in)} \times \text{Length (ft)}}{12}$$
$$\text{Board Feet (when Length is in Inches)} = \frac{\text{Thickness (in)} \times \text{Width (in)} \times \text{Length (in)}}{144}$$
Nominal vs. Actual Softwood Dimensions
| Nominal Size | Actual Size (Surfaced / S4S) | Board Feet per 8-Foot Board (Nominal) |
|---|---|---|
| 1 x 4 | 3/4" × 3-1/2" | 2.67 BF |
| 1 x 6 | 3/4" × 5-1/2" | 4.00 BF |
| 2 x 4 | 1-1/2" × 3-1/2" | 5.33 BF |
| 2 x 6 | 1-1/2" × 5-1/2" | 8.00 BF |
| 2 x 8 | 1-1/2" × 7-1/4" | 10.67 BF |
| 2 x 10 | 1-1/2" × 9-1/4" | 13.33 BF |
| 2 x 12 | 1-1/2" × 11-1/4" | 16.00 BF |
| 4 x 4 | 3-1/2" × 3-1/2" | 10.67 BF |
Understanding Hardwood Quarters (4/4, 8/4)
Hardwood lumber mills sell rough-sawn stock specified in quarter-inches of thickness:
- 4/4 (Four-Quarter): 1 inch thick rough (planes down to approximately 13/16" to 3/4" finished).
- 5/4 (Five-Quarter): 1-1/4 inches thick rough (planes down to roughly 1" to 1-1/16").
- 6/4 (Six-Quarter): 1-1/2 inches thick rough (planes down to roughly 1-1/4").
- 8/4 (Eight-Quarter): 2 inches thick rough (planes down to roughly 1-3/4").
Frequently Asked Questions
What is a board foot (BF)?
A board foot (BF or FBM) is a specialized unit of lumber volume measurement in North America equal to a board that is 1 inch thick, 12 inches wide, and 12 inches long (144 cubic inches, or 1/12 of a cubic foot).
What is the board foot formula?
When length is in feet: Board Feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12. When length is in inches: Board Feet = (Thickness in inches × Width in inches × Length in inches) ÷ 144.
What is the difference between nominal and actual lumber sizes?
Rough-sawn hardwood is sold by nominal thickness (e.g. 4/4 is 1 inch rough, 8/4 is 2 inches rough). Finished softwood dimensional lumber (like a 2x4) is surfaced/planed down to actual dimensions (1.5 inches by 3.5 inches). Hardwood is priced on rough nominal board footage.
Why is hardwood priced by the board foot rather than linear foot?
Hardwood logs yield boards of random widths and lengths depending on the natural log taper. Pricing by board feet accounts for the exact volume of usable timber regardless of whether a plank is 5.5 inches or 9.25 inches wide.
How much waste factor should I add for woodworking?
Add 10% to 15% for standard cabinet and furniture building to account for squaring ends, defects, knots, and planer snipe. For highly figured lumber, curved parts, or rough lumber that requires jointing and surfacing, 20% waste is prudent.
How do I convert board feet to cubic feet or cubic meters?
Since 1 board foot equals 1/12 of a cubic foot ($0.0833\text{ ft}^3$), divide total board feet by 12 to get cubic feet. To convert to cubic meters ($m^3$), multiply board feet by $0.00235974$.