Board foot calculator
Board feet = thickness × width in inches × length in feet ÷ 12: a 2x8 that is 12 ft long is 16 board feet, so 13 of them are 208 board feet.
Example: replace these measurements
Your lumber list
208 board feet+ 1 more item on the list
208 board feet
Your shopping list
- 208 board feet
- 13 2x8 boards, 12 ft
Quantities and package details
- Deck joists
- 13 × 2x8 × 12 ft = 208 board feet
- 2x8 actual size
- 1 1/2 × 7 1/4 in
- Total board feet
- 208
- Linear feet
- 156
- Weight, about
- 446 lb at 19% moisture, 34.3 lb a board
The calculation
- Deck joists: 2 × 8 × 12 ÷ 12 = 16 board feet each × 13 = 208
- Deck joists weight: 11.781 cu ft of wood × 62.43 × 0.51 (southern pine) × 1.19 = 446 lb
Not measured yet? Common sizes
A rough starting point, worked out with this calculator. Nominal sizes, as yards count board feet for softwood lumber. Weights are for southern pine at 19% moisture, from the USDA Wood Handbook. Use a row to load its size into the calculator, then change it to your measurements.
| Board | Actual size | Board feet | Weight | Load |
|---|---|---|---|---|
| 1x6, 8 ft | 3/4 × 5 1/2 in | 4 | 8.7 lb | |
| 2x4, 8 ft | 1 1/2 × 3 1/2 in | 5.33 | 11.1 lb | |
| 2x6, 10 ft | 1 1/2 × 5 1/2 in | 10 | 21.7 lb | |
| 2x8, 12 ft | 1 1/2 × 7 1/4 in | 16 | 34.3 lb | |
| 2x10, 16 ft | 1 1/2 × 9 1/4 in | 26.67 | 58.4 lb | |
| 4x4, 8 ft | 3 1/2 × 3 1/2 in | 10.67 | 25.8 lb | |
| 6x6, 10 ft | 5 1/2 × 5 1/2 in | 30 | 79.6 lb |
Common questions
How do I work out board feet?
Multiply the thickness and width in inches by the length in feet, then divide by 12. A 2x6 that is 10 ft long is 2 × 6 × 10 ÷ 12 = 10 board feet.
How many board feet is a 2x4?
Two thirds of a board foot per foot of length: an 8 ft 2x4 is 2 × 4 × 8 ÷ 12 = 5.33 board feet, counted on its nominal size.
Why is a 2x4 not 2 by 4 inches?
Lumber is named by its size before it is dried and planed. A 2x4 is 1 1/2 × 3 1/2 inches, a 2x6 is 1 1/2 × 5 1/2 and a 1x6 is 3/4 × 5 1/2.
How much does a 2x4 weigh?
About 11 lb for an 8 ft southern pine 2x4 at 19% moisture, the most a board stamped S-DRY may hold: 1 1/2 × 3 1/2 in of wood, 8 ft long, at 37.9 lb a cubic foot (USDA Wood Handbook). A Douglas-fir 2x4 is about 10.4 lb, an Engelmann spruce one 7.6 lb, and pressure-treated lumber fresh from the yard is heavier.
How is hardwood measured?
In board feet of its rough thickness, given in quarters of an inch: 4/4 is 1 inch, 5/4 is 1 1/4 and 8/4 is 2 inches. A 4/4 board 6 inches wide and 8 ft long is 4 board feet.
How to plan the quantity
A board foot is a board 1 inch thick, 12 inches wide and 1 foot long: 144 cubic inches. Board feet = thickness (in) × width (in) × length (ft) ÷ 12, using the nominal size for softwood lumber. A 2x8 that is 12 ft long is 2 × 8 × 12 ÷ 12 = 16 board feet.
Softwood lumber is named by its size before drying and planing: a 2x4 is 1 1/2 × 3 1/2 inches. Yards price it by the piece or by the board foot of the nominal size, so the list shows both.
Hardwood is sold by the board foot of its rough thickness, in quarters: 4/4 is 1 inch, 5/4 is 1 1/4 and 8/4 is 2 inches. Choose “custom” and enter that thickness and the board’s width.
The weight is the wood in each board’s actual size, times the density of its species at your moisture content, from the USDA Wood Handbook: a 12 ft southern pine 2x8 at 19% moisture is about 34 lb. Check it against what your vehicle or trailer may carry before you load up.
Before you order
- This counts the lumber you list; it does not size joists, beams or posts. Your plans and the local code do that.
- Add extra for defects and cuts: about 10% for framing, more for furniture-grade hardwood.