How to calculate board feet
A board foot is a volume: 144 cubic inches, the same as a board 1 inch thick, 12 inches wide and 12 inches long.
Board feet = thickness (in) × width (in) × length (ft) ÷ 12
or thickness × width × length (all in inches) ÷ 144
Ten 1 × 6 boards 8 ft long: 1 × 6 × 8 ÷ 12 = 4 BF each, 40 BF total.
Worked example: pricing walnut for a table top
- Measure each board in its rough size. Five boards of 8/4 walnut, each 2 in thick, 7 in wide and 7 ft long.
- Board feet per board. 2 × 7 × 7 ÷ 12 = 8.17 BF.
- All boards. 8.17 × 5 = 40.8 BF.
- Add waste. Allow 25% for knots, checks and offcuts: 40.8 × 1.25 = 51 BF to buy.
- Price it. At $14 per board foot, about $714.
Board feet in common lumber sizes
| Size | 8 ft | 10 ft | 12 ft | 14 ft | 16 ft |
|---|---|---|---|---|---|
| 2x4 | 5.33 | 6.67 | 8 | 9.33 | 10.67 |
| 2x6 | 8 | 10 | 12 | 14 | 16 |
| 2x8 | 10.67 | 13.33 | 16 | 18.67 | 21.33 |
| 2x10 | 13.33 | 16.67 | 20 | 23.33 | 26.67 |
| 2x12 | 16 | 20 | 24 | 28 | 32 |
Figures use the nominal size, the way lumberyards count board feet. For the real dimensions of each size, see the lumber dimensions chart.
Board feet vs linear feet
A linear foot is just length, whatever the size of the board. A board foot is volume. Construction lumber like 2x4s is usually priced per piece or per linear foot, while hardwood is priced per board foot. To convert: board feet = linear feet × thickness (in) × width (in) ÷ 12. Twenty linear feet of 1x6 is 20 × 1 × 6 ÷ 12 = 10 board feet.
Hardwood thickness: the quarter system
| Quarters | Rough thickness | Typical surfaced (S2S) |
|---|---|---|
| 4/4 | 1" | 13/16" |
| 5/4 | 1-1/4" | 1-1/16" |
| 6/4 | 1-1/2" | 1-5/16" |
| 8/4 | 2" | 1-3/4" |
| 12/4 | 3" | 2-3/4" |
Pricing logs instead of boards? The log weight calculator also estimates Doyle board feet.
More on board feet
The unit is explained in what a board foot is. To convert a store price per piece to a price per board foot, use the lumber cost calculator. To convert to area, use the board feet to square feet calculator. For logs, the log board foot calculator applies the Doyle and International rules.
Frequently asked questions
How many board feet is a 2x4x8?
5.33 board feet using nominal size (2 × 4 × 8 ÷ 12). Construction lumber is usually sold per piece or linear foot, not by the board foot.
How do I convert linear feet to board feet?
Multiply linear feet by thickness and width in inches, then divide by 12.
Is a board foot the same as a square foot?
Only for 1-inch-thick material. A board foot includes thickness; a square foot does not.
How do I figure out board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. A 2 by 6 inch board 10 ft long is 2 × 6 × 10 ÷ 12 = 10 board feet.
How many board feet are in a 1x6x8?
4 board feet, and a 1x12x8 is 8.
Sources
Reference charts
More lumber and wood calculators
Plywood Calculator
Sheets of plywood or OSB for floors, walls and roofs.
Stud Calculator
Studs and plates for any wall.
Firewood Cord Calculator
Check a woodpile in cords and face cords.
Log Weight Calculator
Green weight and Doyle board feet by species.
Lumber Cost Calculator
Price per piece, board foot and linear foot, side by side.
Log Board Foot Calculator
Board feet in a log by two log rules.