The conversion
A board foot is 144 cubic inches, the volume of a board 1 inch thick, 12 inches wide and 12 inches long. One board foot of 1 inch material covers exactly 1 square foot, and the thicker the board the less area one board foot covers.
Square feet = board feet ÷ thickness (in)
Board feet = square feet × thickness (in)
Linear feet = square feet × 12 ÷ width (in)
100 board feet of 1 inch lumber covers 100 sq ft. The same 100 board feet of 2 inch lumber covers 50 sq ft. If the boards are 6 inches wide, 100 sq ft of 1 inch stock is 200 linear feet.
Square feet covered by 100 board feet
| Thickness | Quarters | Sq ft per 100 BF | BF per 100 sq ft |
|---|---|---|---|
| 0.75 in | 3/4 | 133.3 | 75 |
| 1 in | 4/4 | 100.0 | 100 |
| 1.25 in | 5/4 | 80.0 | 125 |
| 1.5 in | 6/4 | 66.7 | 150 |
| 2 in | 8/4 | 50.0 | 200 |
| 3 in | 12/4 | 33.3 | 300 |
For flooring and paneling, buy more than the area: a common allowance is 10 to 15% for waste and cuts, and more for hardwood where you cut out defects. Lumberyards usually price on nominal, rough thickness, so a board planed down to 13/16 inch still counts as 4/4. Pricing from a quote? The lumber cost calculator converts price per piece to price per board foot.
For one board or a stack priced by volume, use the board foot calculator. See what a board foot is for the background.
Frequently asked questions
How many square feet is 100 board feet?
100 sq ft at 1 inch thick, 50 sq ft at 2 inches and 133 sq ft at 3/4 inch.
How do I convert square feet to board feet?
Multiply the area in square feet by the thickness in inches. 100 sq ft of 2 inch lumber is 200 board feet.
How many linear feet is 100 board feet?
It depends on size. With 1 inch thick, 6 inch wide boards, 100 board feet is 200 linear feet.
Sources
Reference charts
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