Thickness and width accept decimals or fractions, such as 0.75 or 3/4. For hardwood sold in quarters, enter the quarter size: 4/4 is 1, 5/4 is 1.25, 8/4 is 2.
The board foot formula
A board foot is 144 cubic inches of wood, the volume of a board 1″ thick, 12″ wide, and 12″ long:
- Length in inches: board feet = T × W × L ÷ 144
- Length in feet: board feet = T × W × L ÷ 12
Example: a 4/4 cherry board 7″ wide and 6 feet long is 1 × 7 × 6 ÷ 12 = 3.5 board feet. At $9 per board foot, it costs $31.50.
Board feet of common boards
Calculated from nominal sizes, the way softwood lumber is usually priced.
| Board | 8 ft | 10 ft | 12 ft |
|---|---|---|---|
| 1x4 | 2.67 | 3.33 | 4 |
| 1x6 | 4 | 5 | 6 |
| 1x8 | 5.33 | 6.67 | 8 |
| 1x12 | 8 | 10 | 12 |
| 2x4 | 5.33 | 6.67 | 8 |
| 2x6 | 8 | 10 | 12 |
| 2x8 | 10.67 | 13.33 | 16 |
| 2x10 | 13.33 | 16.67 | 20 |
| 2x12 | 16 | 20 | 24 |
| 4x4 | 10.67 | 13.33 | 16 |
Nominal or actual size?
Lumber is normally priced on nominal dimensions. Softwood dimensional lumber uses its nominal size: a 2x4 counts as 2″ × 4″, even though it measures 1½″ × 3½″. Rough hardwood uses its quarter thickness (4/4 counts as 1″) and the board’s measured width. Suppliers can differ, so ask how yours measures. Our lumber sizes chart lists the actual sizes.
Questions
What is a board foot?
A board foot is a volume of wood equal to 144 cubic inches: a board 1 inch thick, 12 inches wide, and 12 inches long.
What is the board foot formula?
Board feet = thickness (in) × width (in) × length (in) ÷ 144. With the length in feet, it is thickness × width × length (ft) ÷ 12.
How many board feet are in a 2x4x8?
Using nominal dimensions, a 2x4 that is 8 feet long is 2 × 4 × 96 ÷ 144 = 5.33 board feet.
Do I use nominal or actual size for board feet?
Lumber is usually sold by nominal size: softwood dimensional lumber by its nominal thickness and width, and rough hardwood by its quarter thickness (4/4 = 1 inch) and measured width. Check how your supplier calculates it.
How do I convert board feet to linear feet?
Linear feet = board feet × 12 ÷ (thickness × width in inches). For example, 10 board feet of 1x6 is 10 × 12 ÷ 6 = 20 linear feet.
The cut list calculator tells you how many boards a list of cuts needs, and our free plans include a full shopping list.