Enter the quantity, thickness, width and length of your boards. Add a row for each size, and the calculator adds up the board feet and the cost.
Cost
Dimensional lumber is usually counted by its nominal size (a 2×4 counts as 2 by 4 inches). Hardwood is measured in quarters: 4/4 is 1 inch thick.
What is a board foot?
A board foot is a volume of wood 12 inches long, 12 inches wide and 1 inch thick, or 144 cubic inches. Lumber yards use it to price hardwood and some softwood, because it accounts for thickness, width and length at the same time.
Board foot formula
- Board feet = thickness (in) × width (in) × length (ft) ÷ 12
- With the length in inches: thickness × width × length ÷ 144
Worked example
- 10 boards of 2×4, 8 ft long: 2 × 4 × 8 ÷ 12 = 5.33 board feet each, 53.3 in total
- 4 boards of 1×6, 10 ft long: 1 × 6 × 10 ÷ 12 = 5 board feet each, 20 in total
- Total: 73.3 board feet. At $3.50 per board foot, about $257.
Board feet for common sizes
| Board | Board feet per piece |
|---|---|
| 1×6, 8 ft | 4 |
| 2×4, 8 ft | 5.33 |
| 2×6, 8 ft | 8 |
| 4×4, 8 ft | 10.67 |
| 2×8, 10 ft | 13.33 |
| 2×10, 12 ft | 20 |
| 2×12, 16 ft | 32 |
Nominal sizes and hardwood quarters
Softwood dimensional lumber is sold by its nominal size: a 2×4 is really about 1½ × 3½ inches, but it’s counted as 2 × 4 for board feet. Hardwood is measured in quarters of an inch: 4/4 is 1 inch, 5/4 is 1¼ inches, 6/4 is 1½ inches and 8/4 is 2 inches thick. Enter the nominal or quarter thickness, as the lumber yard does.
Board feet, linear feet and cubic feet
- Linear feet only measure length. The linear foot calculator works those out.
- Cubic feet: 12 board feet make 1 cubic foot.
Frequently asked questions
How do I calculate board feet?
Multiply thickness in inches × width in inches × length in feet, then divide by 12.
How many board feet are in a 2×4×8?
5.33 board feet, using the nominal 2 × 4 inch size.
How many board feet are in a cubic foot?
12 board feet.
Do I use actual or nominal size?
Lumber yards use the nominal size for softwood and the rough quarter thickness for hardwood. Use the same sizes your yard quotes.
How do I price lumber by the board foot?
Multiply the total board feet by the price per board foot. Enter the price above to see the total.
Results are exact for the sizes you enter. See How We Calculate for the formulas we use.
