Board Foot Calculator
Calculate board feet (BF or FBM), whole pieces with an allowance, cubic volume and lumber cost from thickness, width, length and quantity.
Board foot formulas
One board foot is a volume of 12 in × 12 in × 1 in = 144 cubic inches. It equals 1/12 cubic foot or 0.002359737216 m³.
For dimensions in inches and feet:
Board feet per piece = thickness (in) × width (in) × length (ft) ÷ 12.
Total board feet = board feet per piece × quantity.
For metric dimensions:
Board feet = [thickness (m) × width (m) × length (m)] ÷ 0.002359737216.
The allowance is converted to whole additional pieces: pieces to order = ceiling(quantity × (1 + allowance % ÷ 100)). Cost = ordered board feet × entered price per board foot.
Six calculated examples
| Dimensions and quantity | Board feet before allowance |
|---|---|
| 1 in × 6 in × 8 ft; 10 boards | 40 BF |
| 2 in × 6 in × 8 ft; 10 boards | 80 BF |
| 2 in × 4 in × 12 ft; 5 boards | 40 BF |
| 1.5 in × 7.25 in × 10 ft; 8 boards | 72.5 BF |
| 50 mm × 150 mm × 2.4 m; 10 boards | 76.28 BF |
| 25 mm × 100 mm × 3 m; 20 boards | 63.57 BF |
How to use the calculator
- Select the unit system and enter one board’s thickness, width and length.
- Enter the number of boards with those same dimensions.
- Add an allowance only when you want whole spare pieces. Enter zero for the measured quantity alone.
- Optionally enter the supplier’s price per board foot. Keep all pricing in one currency.
- Calculate separate groups when thickness, width or length changes, then add their board-foot totals.
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Buying trim or dimensional stock by length? Use the Linear Feet Calculator for total length, waste, whole stock pieces and cost.