Board Foot Calculator
Use this board foot calculator to find how much lumber you have or need. Enter thickness, width, length and quantity to get total board feet, the cost at your price per board foot, and the equivalent cubic feet and cubic meters. One board foot is 144 cubic inches.
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Total board feet
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Board feet per piece
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Estimated cost
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Cubic feet (cu ft)
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Cubic meters (m³)
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Cubic inches (cu in)
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Board feet per piece = thickness (in) × width (in) × length (ft) ÷ 12, because 1 board foot = 144 cubic inches (12 in × 12 in × 1 in). Lumber is sold by nominal size (a 2×6) but measures less (1.5 × 5.5 in). Actual size gives the true wood volume; some suppliers price by nominal size, so check which one yours uses. Cubic feet = board feet ÷ 12.
Nominal vs actual lumber sizes
| Nominal | Actual (in) |
|---|---|
| 1×4 | 0.75 × 3.5 |
| 1×6 | 0.75 × 5.5 |
| 1×8 | 0.75 × 7.25 |
| 1×12 | 0.75 × 11.25 |
| 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 |
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How it works
- What is a board foot?
- A board foot is a unit of lumber volume equal to 144 cubic inches, such as a board 1 in thick, 12 in wide and 12 in (1 ft) long. A 1 in × 12 in board that is 8 ft long is 8 board feet.
- How do you calculate board feet?
- Multiply thickness in inches by width in inches by length in feet, then divide by 12. A 2×6 with actual size 1.5 × 5.5 in and 8 ft long is 1.5 × 5.5 × 8 ÷ 12 = 5.5 board feet.
- Should I use nominal or actual size?
- Actual size gives the true volume of wood. Some lumber is priced by nominal size, so a nominal 2×6 that is 8 ft long counts as 2 × 6 × 8 ÷ 12 = 8 board feet. Ask your supplier which method it uses.
- How do you find the cost of lumber per board foot?
- Multiply total board feet by the price per board foot. Ten 2×6 boards at 8 ft are 55 board feet using actual size, which costs $137.50 at $2.50 per board foot.
- How many board feet are in a cubic foot?
- There are 12 board feet in one cubic foot, because a cubic foot is 1,728 cubic inches and 1,728 ÷ 144 = 12. One cubic meter is about 423.8 board feet.