Board Foot Calculator - Lumber Volume & Cost
Board Foot Calculator
Measure lumber the way sawmills sell it
The Lumber Unit
A board foot is 144 cubic inches: a board 1 inch thick, 12 inches wide and 1 foot long.
Many Boards at Once
Add a line for each size, with quantities, and see each line and the grand total.
Cost and Cubic Metres
Add a price per board foot for the total cost, and see the equivalent volume in cubic metres.
Full Privacy
Everything is calculated in your browser.
The Board Foot Formula
Board feet = thickness (in) × width (in) × length (ft) ÷ 12. A 2 × 4 that is 8 feet long is 2 × 4 × 8 ÷ 12 = 5.33 board feet, so ten of them are 53.3 board feet, and at $4.50 per board foot they cost about $240. Hardwood is commonly priced per board foot, while softwood construction lumber is usually sold by the piece or the linear foot.
Use the nominal size (for example 1 in) for rough or dimensioned-as-sold lumber, since that is what the price is based on, and the actual size for finished stock if that is how it is priced. Real boards are often thinner and narrower than their nominal names, and a 2 × 4 is really about 1.5 × 3.5 inches. Add 10 to 20% for waste when planning a project.
Key Takeaways
- Exact formula: Each line uses thickness × width × length ÷ 12, times the quantity.
- Volume conversion: 1 board foot is 0.00236 cubic metres.
- Checked inputs: Incomplete lines and zero sizes are reported.