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Board Foot Calculator
Calculate board feet for lumber purchases and pricing. Estimate costs and quantities for your woodworking projects.
Board Foot Calculator
Calculate lumber volume in board feet and estimate costs
What Is a Board Foot?
A board foot (abbreviated BF or BDFT) is the standard unit of measurement for lumber volume in North America. One board foot equals a piece of wood that is 1 inch thick, 12 inches wide, and 12 inches long — or 144 cubic inches of wood.
Lumber yards, sawmills, and hardwood dealers price wood by the board foot. Understanding this measurement is essential for accurately estimating material costs on construction and woodworking projects.
Board Foot Formula
Where thickness and width are in inches, and length is in inches. If length is in feet, divide by 12 instead of 144.
Common Lumber Board Feet Reference
Quick reference for board feet per linear foot of common lumber sizes. Note: nominal sizes (like 2×4) are larger than actual dimensions.
| Nominal Size | Actual Size (in) | BF per Linear Foot | BF in 8' Board | BF in 12' Board |
|---|---|---|---|---|
| 1×4 | ¾ × 3½ | 0.33 | 2.67 | 4.00 |
| 1×6 | ¾ × 5½ | 0.50 | 4.00 | 6.00 |
| 1×8 | ¾ × 7¼ | 0.67 | 5.33 | 8.00 |
| 1×12 | ¾ × 11¼ | 1.00 | 8.00 | 12.00 |
| 2×4 | 1½ × 3½ | 0.67 | 5.33 | 8.00 |
| 2×6 | 1½ × 5½ | 1.00 | 8.00 | 12.00 |
| 2×8 | 1½ × 7¼ | 1.33 | 10.67 | 16.00 |
| 2×10 | 1½ × 9¼ | 1.67 | 13.33 | 20.00 |
| 2×12 | 1½ × 11¼ | 2.00 | 16.00 | 24.00 |
| 4×4 | 3½ × 3½ | 1.33 | 10.67 | 16.00 |
| 6×6 | 5½ × 5½ | 3.00 | 24.00 | 36.00 |
How to Calculate Board Feet: Step by Step
Example 1: How many board feet in a 2×4×8?
A standard 2×4 that is 8 feet long:
Using nominal dimensions (2×4) for pricing, since that's how lumber yards sell it.
Example 2: How many board feet in a 2×6?
A 2×6 that is 12 feet long:
Example 3: Hardwood pricing
A ¾" thick walnut board, 8 inches wide, 6 feet long at $12/BF:
Cost = 3.00 × $12.00 = $36.00
Board Foot Calculator FAQ
What is a board foot of lumber?
A board foot is a unit of volume equal to 144 cubic inches of wood — equivalent to a 1-inch thick board that is 12 inches wide and 12 inches long. It's the standard measurement for buying and selling hardwood lumber in the United States and Canada.
How many board feet is a 2×4×8?
A 2×4 that is 8 feet long contains 5.33 board feet. The calculation is (2 × 4 × 8) ÷ 12 = 5.33 BF. Lumber yards typically use nominal dimensions for pricing.
How many board feet are in a 2×6?
It depends on the length. A 2×6×8 has 8 board feet. A 2×6×10 has 10 board feet. A 2×6×12 has 12 board feet. The formula is (2 × 6 × length in feet) ÷ 12.
How do you calculate board feet for spray foam?
Spray foam insulation uses "board foot" differently — it means 1 square foot of coverage at 1 inch thick. To calculate: multiply the square footage of the area by the thickness in inches. For example, a 1,000 sq ft area sprayed 3 inches thick = 3,000 board feet of spray foam.
What is the difference between a board foot and a linear foot?
A linear foot measures only length (12 inches), while a board foot measures volume (144 cubic inches). A 2×6 has 1 board foot per linear foot, but a 2×12 has 2 board feet per linear foot because it's wider.
How much does a board foot of lumber cost?
Prices vary by species. Common softwoods like pine cost $2-5 per board foot. Hardwoods like oak or maple run $4-10 per BF. Exotic species like walnut or cherry can be $8-15+ per board foot. Prices change with market conditions.
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