Board Foot Calculator · https://calcnaut.com/board-foot-calculator/
Board Foot Calculator
Work out the board feet in a piece of lumber, or a whole stack, from its thickness, width and length. A board foot is 144 cubic inches, the volume of a 1 inch by 12 inch board one foot long, and it is how hardwood is sold. Enter your boards, pick whether the length is in feet or inches, add a waste allowance and a price per board foot, and the calculator returns the total board feet and cost. The formula is shown so you can check the math.
This is an estimate, not professional advice. Check your inputs and verify the result against your plans and local building code before you build or order. See terms and disclaimer.
How this calculator works
Enter the thickness and width in inches and the length, then the number of boards. The board feet update instantly, along with the cubic feet and the cost if you enter a price per board foot. Use the quarter sizes (4/4, 5/4, 8/4) for rough hardwood, which is sold at full thickness. Add a waste allowance for the offcuts and defects you cannot use.
Length in feet
Board feet (each) = Thickness(in) × Width(in) × Length(ft) ÷ 12Total = Board feet × Boards × (1 + Waste% ÷ 100) Cost = Total × Price/BFLength in inches
Board feet (each) = Thickness(in) × Width(in) × Length(in) ÷ 144Total = Board feet × Boards × (1 + Waste% ÷ 100)Worked example
An 8 ft long, 6 in wide, 1 in thick board (Length in feet), giving 4 board feet. Inputs: Thickness 1 in, Width 6 in, Length 8 ft, Number of boards 1, Waste allowance 0 %. Result: 4 BF.
Board feet for common boards
Length in feet, single board, no waste. Tap a row to load it in the calculator above.
| Board | Board feet (BF) | |
|---|---|---|
| 1 × 4 × 8 ft | 2.67 | Use → |
| 1 × 6 × 8 ft | 4 | Use → |
| 1 × 8 × 8 ft | 5.33 | Use → |
| 1 × 12 × 8 ft | 8 | Use → |
| 2 × 6 × 8 ft | 8 | Use → |
| 2 × 8 × 10 ft | 13.33 | Use → |
| 8/4 × 10 × 12 ft | 20 | Use → |
Method & assumptions
A board foot is the standard unit of volume for lumber in North America. One board foot is 144 cubic inches, the amount of wood in a board 1 inch thick, 12 inches wide and 12 inches long. A 1 by 12 board one foot long is one board foot, and so is a 2 by 6 of the same length, because both contain the same volume of wood. Hardwood and rough-sawn lumber are priced by the board foot, not by the linear foot, which is why this number matters when you buy.
The formula is thickness in inches times width in inches times length in feet, divided by 12. If you measure the length in inches instead, divide by 144, since there are 144 cubic inches in a board foot. Multiply by the number of boards for a full order. The result is a measure of volume, so it captures thickness and width that linear feet ignore: a 10 foot 2 by 6 is 10 linear feet but only 10 board feet, while a 10 foot 1 by 4 is the same 10 linear feet but just 3.3 board feet.
One detail trips people up: nominal versus actual size. Rough-sawn hardwood is usually sold at full, nominal dimensions, so a 4/4 board really is one inch thick and you use that figure. Dressed construction softwood is smaller than its name, a 2 by 4 actually measures 1.5 by 3.5 inches, so for an accurate volume use the milled size your supplier quotes. The quarter sizes (4/4, 5/4, 8/4) in the thickness presets are the hardwood convention, where 4/4 means four quarters of an inch, or one inch. Add a waste allowance of 10 to 20 percent for hardwood, because boards have defects, splits and wane that you cut away, and always confirm the price basis with your dealer.
Pro tips and common mistakes
- Board feet measure volume, not length. Two boards can be the same length but very different board feet. A 2 by 6 has four times the wood of a 1 by 3 of the same length, and you pay for the volume.
- Use the quarter sizes for hardwood. Rough hardwood is sold in quarters of an inch: 4/4 is 1 inch, 5/4 is 1.25, 8/4 is 2. It is usually sold at full nominal thickness, so use those figures, not a dressed size.
- Watch nominal versus actual on softwood. A construction 2 by 4 is really 1.5 by 3.5 inches after milling. For an accurate volume on dressed lumber, enter the actual measured size, not the name on the tag.
- Add waste for defects. Hardwood has knots, splits and wane you cut around, so order 10 to 20 percent over your finished board feet. Rough lumber needs more than clear, select grades.
- Board feet is not the same as a cubic foot. There are 12 board feet in a cubic foot of solid wood. The calculator shows both, which is handy when a supplier or a shipping quote uses cubic feet or cubic meters.
Frequently asked questions
How do I calculate board feet?
What is one board foot?
What is the difference between board feet and linear feet?
Should I use nominal or actual size for board feet?
What does 4/4 mean in lumber?
References
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