Board Foot
Definition
A board foot (BF) is the standard unit of measurement for lumber volume in the United States. One board foot equals a piece of wood 12 inches long × 12 inches wide × 1 inch thick (144 cubic inches). Hardwood lumber is almost always priced per board foot, while dimensional softwood framing lumber is priced per linear foot or per piece. To calculate board feet: (Thickness in inches × Width in inches × Length in feet) ÷ 12. For example, an 8-foot-long 2×6 contains 8 board feet.
Why is Board Foot Important?
For homeowners, contractors, and DIY builders across the United States, understanding Board Foot is essential to accurate material estimation and cost planning. Whether you are pouring a concrete driveway, framing a deck, or calculating roofing materials, mastering this concept helps prevent costly over-ordering or project delays from material shortages.
Our free construction calculators leverage this concept to provide instant, accurate estimates — saving hours of manual measurement and arithmetic while ensuring your project stays on budget.
What is a Board Foot?
A board foot (BF or BDFТ) is the standard unit of volume measurement for lumber in the United States. One board foot equals a piece of wood measuring 12 inches long × 12 inches wide × 1 inch thick — equivalent to 144 cubic inches of wood.
Board feet are primarily used for pricing and measuring hardwood lumber (oak, maple, walnut, cherry) and specialty softwoods. Standard dimensional softwood lumber (2×4s, 2×6s) at big-box stores is typically sold by the linear foot or per piece, not by board feet.
How to Calculate Board Feet
Formula:
Board Feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12
| Lumber Size | Length | Board Feet | Calculation |
|---|---|---|---|
| 1" × 12" | 8 ft | 8 BF | (1 × 12 × 8) ÷ 12 |
| 2" × 6" | 8 ft | 8 BF | (2 × 6 × 8) ÷ 12 |
| 2" × 4" | 10 ft | 6.67 BF | (2 × 4 × 10) ÷ 12 |
| 4" × 4" | 8 ft | 10.67 BF | (4 × 4 × 8) ÷ 12 |
| 1" × 6" | 12 ft | 6 BF | (1 × 6 × 12) ÷ 12 |
| 2" × 12" | 16 ft | 32 BF | (2 × 12 × 16) ÷ 12 |
Nominal vs Actual Dimensions
An important nuance: board foot calculations use nominal dimensions (the named size), not actual milled dimensions. A "2×4" actually measures 1.5" × 3.5" after surfacing, but board feet are calculated using the 2" × 4" nominal size.
| Nominal Size | Actual Size (Surfaced) | Difference |
|---|---|---|
| 1" (4/4) | ¾" (13/16" rough) | ¼" lost to surfacing |
| 2" | 1½" | ½" lost |
| 4" | 3½" | ½" lost |
| 6" | 5½" | ½" lost |
| 8" | 7¼" | ¾" lost |
| 12" | 11¼" | ¾" lost |
Hardwood Lumber Pricing (2024 US Averages)
| Species | Grade | Price per Board Foot |
|---|---|---|
| Red Oak | FAS (Select) | $4.50–$7.00 |
| Hard Maple | FAS | $5.00–$8.00 |
| Black Walnut | FAS | $8.00–$14.00 |
| Cherry | FAS | $5.50–$9.00 |
| White Ash | FAS | $3.50–$6.00 |
| Poplar | FAS | $2.50–$4.50 |
FAS = First and Seconds, the highest hardwood grade. Prices vary significantly by region, supplier, and market conditions.