Quick Board Foot Calculator Guide
Use this handy tool to figure out exactly how much lumber you’ll need before you buy. If you already know what a board foot is, just enter your board’s dimensions below. Otherwise, read on for the basics!
What Is a Board Foot?
A board foot measures volume rather than area. It’s the industry standard for buying lumber because boards come in many widths and thicknesses. One board foot equals a piece of wood that is:
- 1 ft long
- 1 ft wide
- 1 in thick
That works out to:
1 board foot = 144 cubic inches = 1/12 cubic feet
How to Calculate Board Feet
It’s as simple as plugging your measurements into this formula:
board feet = length (ft) × width (in) × thickness (in) / 12
$$\text{board feet} = \frac{\text{length (ft)} \times \text{width (in)} \times \text{thickness (in)}}{12}$$
Remember: Length in feet; width & thickness in inches.
Example Calculation
Imagine you need 4 oak boards for a project. Each board is:
- Length: 6 ft
- Width: 8 in
- Thickness: 1 ½ in
Per board
$$\displaystyle \frac{6 \times 8 \times 1.5}{12} = 6.0\;\mathrm{BF}$$
Total for 4 boards
$$\displaystyle 6.0 \times 4 = 24.0\;\mathrm{BF}$$
Cost at \$5.25 per BF
$$\displaystyle 24.0 \times 5.25 = \$126.00$$
💡 You might also like our Decking Calculator or Plywood Yield Calculator for related projects.
Frequently Asked Questions
How do I estimate board feet in a log?
Use a log‑rule chart (Doyle, Scribner, etc.), or estimate with:
$$\displaystyle \biggl(\frac{\text{Diameter (in)} - 4}{4}\biggr)^{2} \times \text{Length (ft)} $$
This gives you an approximate BF before milling.
What’s the difference between board feet and linear feet?
- Board feet measure volume.
- Linear feet measure length.
For instance, an 8 ft × 2 in × 4 in 2×4 is 8 LF, but:
$$\displaystyle \frac{8 \times 2 \times 4}{12} \;=\; 5.33\;\mathrm{BF} $$
How many BF in a 2×6?
How many board feet are in a 2 × 4?
| Length of 2 × 4 (ft) | Number of board feet |
|---|---|
| 6 | 4 |
| 8 | 5⅓ |
| 10 | 6⅔ |
| 12 | 8 |
| 14 | 9⅓ |
| 16 | 10⅔ |
| 18 | 12 |
| 20 | 13⅓ |
| 22 | 14⅔ |
| 24 | 16 |
How do I measure a board foot?
- Measure board length in feet.
- Measure width in inches.
- Measure thickness in inches.
- Multiply them and divide by 12.
How much does a board foot of oak weigh?
Oak averages about 4.0 lb per BF (1.8 kg), depending on species and moisture.
Can I convert square feet to board feet?
Yes—if you include thickness.
E.g. 200 ft² at ¾ in thick =
$$\displaystyle \frac{200 \times 0.75}{12} \;=\; 12.5\;\mathrm{BF} $$