Board Foot Calculator
Work out board feet from a board's nominal thickness, width and length, the unit lumber yards use to price boards.
Calculator
| Linear feet | 8.0 ft |
|---|---|
| Cubic feet of lumber | 0.44 ft³ |
How it is calculated
Board feet = thickness × width × length ÷ 12 × number of boards = 2 × 4 × 8 ÷ 12 × 1 = 5.33 board feet. One board foot is 144 cubic inches (1 inch × 12 inches × 12 inches), so 5.33 board feet is 0.44 cubic feet.
About this calculator
A board foot is a unit of lumber volume: a piece 1 inch thick, 12 inches wide and 12 inches long, or 144 cubic inches. Lumber yards, especially for hardwoods, often price by the board foot.
The formula is thickness (in) × width (in) × length (ft) ÷ 12, using the nominal size, so a '2x4' counts as 2 by 4 even though the actual board is smaller.
Worked examples
| Project | Board feet |
|---|---|
| 1 nominal 2x4 board, 8 ft long | 5.33 bf |
| 20 nominal 2x4 boards, 8 ft long | 106.67 bf |
| 10 nominal 1x6 boards, 12 ft long | 60.00 bf |
| 1 nominal 4x4 board, 10 ft long | 13.33 bf |
Notes
- Prices per board foot vary widely by species and grade; ask the lumber yard.
- Buy extra for knots, splits and cuts: 10 percent or more is common.
- Framing lumber is usually priced per piece or linear foot rather than per board foot.
Quick answers by size
Click one for the exact answer.
How to measure and use this calculator
- Use the nominal thickness and width of the board, such as 2 and 4 for a '2x4'.
- Enter the length in feet and the number of boards.
- Read the board feet; multiply by the price per board foot for a rough cost.
- Add 10 percent or more for waste.
Common mistakes
- Using the actual dimensions (1.5 by 3.5 for a 2x4) instead of the nominal ones.
- Entering length in inches instead of feet.
- Forgetting waste and defects in the boards.
Tips
- Board feet use the nominal size (a '2x4'), not the smaller actual size.
- One board foot is a piece 1 inch thick, 12 inches wide and 12 inches long, which is 144 cubic inches.
- Hardwoods are commonly sold by the board foot; framing lumber is usually sold by the piece or the linear foot.
Frequently asked questions
How many board feet are in a 2x4 that is 8 feet long?
2 × 4 × 8 ÷ 12 = 5.33 board feet.
What is the formula for board feet?
Thickness in inches × width in inches × length in feet ÷ 12, multiplied by the number of boards.