Board Foot Calculator
Calculate board feet from thickness, width, length and quantity.
Project details
Enter your measurements below.
Board feet measure lumber volume, not the length of a board
A board foot is a volume unit used in lumber trade, especially for rough-sawn hardwoods. One board foot represents 144 cubic inches of wood. That means thickness matters just as much as width and length. A 2-inch-thick board contains twice the board-foot volume of a 1-inch board with the same face dimensions. Use the dimensions your supplier prices from—often rough or nominal thickness rather than finished planed size—and keep board-foot calculations separate from a cut list.
1 board foot = 144 cubic inches of lumber volume.
Doubling thickness doubles board-foot volume for the same width and length.
Board feet helps compare volume/pricing; it does not tell you how many usable project pieces can be cut.
How to use the Board Foot Calculator
- Enter board thickness and width in inches, length in feet, and the number of identical boards.
- Confirm whether the supplier prices from rough, nominal or finished dimensions and use the matching dimensions.
- Apply the board-foot formula to one board and multiply by quantity.
- Use the total to compare lumber pricing, then build a separate cut list for actual parts and defects.
Why the divisor is 12 in the common formula
Length is entered in feet while thickness and width are in inches. Dividing by 12 handles both the foot-to-inch conversion and the 144-cubic-inch definition.
Use board feet for purchasing context
Multiply total board feet by a supplier's price per board foot when appropriate, but remember that grade, species, width premiums and milling can affect actual price.
Worked example: four 6/4 boards
- Thickness
- 1.5 in
- Width
- 8 in
- Length
- 10 ft
- Quantity
- 4
One board is 1.5 × 8 × 10 ÷ 12 = 10 board feet. Four identical boards total 40 board feet before considering defects, trimming or the specific supplier's tally method.
Practical planning tips
Use the thickness the supplier uses for tally/pricing. Rough 6/4 stock may be priced differently from its final planed thickness.
Measure wide/random-width hardwood boards individually when widths vary significantly instead of using one average.
Keep a cut-list waste allowance separate from the pure board-foot tally so you can see what is geometry and what is purchasing strategy.
For softwood framing sold by piece rather than board foot, a linear/piece calculator may be more useful.
Common mistakes to avoid
Confusing board feet with linear feet.
Using finished thickness when the supplier prices rough nominal thickness without realizing the difference.
Forgetting to multiply by board quantity.
Treating a board-foot total as proof that the stock dimensions can produce every required cut.
Board Foot Calculator FAQs
What is one board foot?+
It is a lumber volume equal to 144 cubic inches, such as a board 1 inch thick × 12 inches wide × 12 inches long.
Can I use nominal lumber sizes?+
Use the dimensions relevant to how the lumber is sold or tallied. Rough hardwood is often priced from nominal/rough dimensions rather than finished size.
Is board foot the same as square foot?+
No. Square foot measures surface area; board foot includes thickness and therefore measures volume.
Can I calculate price from board feet?+
Yes when the supplier prices by board foot, but species, grade, width and milling may also affect the actual invoice.