Board Foot Calculator
Enter each board's size and count. Get the total board feet to pay for.
100% in your browser - no upload, no sign-up.
Board feet
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💡 Buy 15-20% extra - planing and defects eat into rough lumber.
⚠️ Enter the rough thickness - lumber is sold at pre-planing size.
How to use this board foot calculator
- Enter the board's thickness and width in inches.
- Enter its length in feet and how many boards you're buying.
- Read the total board feet - it updates live.
How board feet are calculated
One board foot is a piece of lumber 1 inch thick, 12 inches wide and 1 foot long. The board-foot volume is thickness (in) × width (in) × length (ft), divided by 12, times the number of pieces. Use nominal (rough) thickness for pricing - a rough 4/4 board is 1 inch. Because rough lumber has defects and loses volume to planing and cutting, buy 15–20% extra over your finished need.
Frequently asked questions
- What is a board foot?
- A board foot is a unit of lumber volume equal to a board 1 inch thick, 12 inches wide and 1 foot long (144 cubic inches). Hardwood is priced per board foot, so it lets you compare boards of different sizes on the same basis.
- How do I calculate board feet?
- Multiply thickness in inches by width in inches by length in feet, then divide by 12, and multiply by the number of boards. A 1 × 6 board 8 ft long is (1 × 6 × 8) ÷ 12 = 4 board feet; ten of them is 40. Enter your dimensions above.
- How much extra lumber should I buy?
- Plan for 15–20% over your finished board-foot total. Rough lumber shrinks when you plane it flat and square, boards have knots and checks you cut around, and offcuts add up - so order more than the exact figure.
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