Board Foot Calculator
Enter your dimensions and get board feet, square footage and cost instantly.
Nominal is the rough-sawn size board feet is based on; actual is the finished planed size.
- Square feet
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- Linear feet
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- Volume (cubic inches)
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- Total cost
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Common Lumber Sizes & Board Feet
| Nominal size | Actual size (in) | Per 8 ft | Per 10 ft | Per 12 ft |
|---|---|---|---|---|
| 1x4 | 0.75 x 3.5 | 2.67 | 3.33 | 4 |
| 1x6 | 0.75 x 5.5 | 4 | 5 | 6 |
| 1x8 | 0.75 x 7.25 | 5.33 | 6.67 | 8 |
| 1x10 | 0.75 x 9.25 | 6.67 | 8.33 | 10 |
| 1x12 | 0.75 x 11.25 | 8 | 10 | 12 |
| 2x4 | 1.5 x 3.5 | 5.33 | 6.67 | 8 |
| 2x6 | 1.5 x 5.5 | 8 | 10 | 12 |
| 2x8 | 1.5 x 7.25 | 10.67 | 13.33 | 16 |
| 2x10 | 1.5 x 9.25 | 13.33 | 16.67 | 20 |
| 2x12 | 1.5 x 11.25 | 16 | 20 | 24 |
| 4x4 | 3.5 x 3.5 | 10.67 | 13.33 | 16 |
| 6x6 | 5.5 x 5.5 | 24 | 30 | 36 |
How to Calculate Board Feet
A board foot is a unit of lumber volume equal to 144 cubic inches — a board 1 inch thick, 12 inches wide, and 1 foot long. The formula is (thickness in inches × width in inches × length in feet) ÷ 12. Multiply by quantity for the total. Use nominal dimensions for board feet, since lumber is sold by nominal size.
Frequently Asked Questions
How do you calculate board feet?
Multiply the thickness in inches by the width in inches by the length in feet, then divide by 12. A 2×4 board 8 feet long is (2 × 4 × 8) ÷ 12 = 5.33 board feet. One board foot equals 144 cubic inches.
What is the difference between a board foot and a square foot?
A board foot is a volume of 144 cubic inches, accounting for thickness, width, and length. A square foot measures surface area only. To convert board feet to square feet, divide by thickness in inches. For example, 10 board feet at 2 inches thick covers 5 square feet.
Should I use nominal or actual lumber dimensions?
Use nominal dimensions, because board feet and lumber pricing are based on nominal size. A nominal 2×4 actually measures 1.5 × 3.5 inches after surfacing, but it is still calculated and sold as a 2×4. Use actual dimensions only when estimating weight or finished space.
How many board feet are in a 2x4x8?
A 2×4 board that is 8 feet long contains 5.33 board feet, calculated as (2 × 4 × 8) ÷ 12. The board's actual size is 1.5 × 3.5 inches, but board feet uses the nominal 2 × 4. The formula is thickness × width × length ÷ 12.
Can I calculate the cost per board foot?
Yes. Divide the total cost of the lumber by its total board feet. For example, $110 divided by 20 board feet equals $5.50 per board foot. Use the price field above to get an instant total. You can also price per linear foot instead.