About this calculator
A board foot is the standard volume unit for lumber in the US and Canada: a piece 12 in wide, 12 in long and 1 in thick, or 144 cubic inches. Hardwood dealers price almost everything by the board foot, so converting a cut list into board feet is the first step in any furniture or cabinet budget.
How to use it
- Enter the thickness. Hardwood is sold by quarters of an inch in rough thickness: 4/4 is 1 in, 5/4 is 1¼ in, 8/4 is 2 in.
- Enter the width in inches and the length in feet.
- Enter the number of boards of that size.
- Add the price per board foot to see the total cost.
The formula
Board feet = thickness (in) × width (in) × length (ft) ÷ 12
= thickness (in) × width (in) × length (in) ÷ 144
A 1 × 6 in board 8 ft long is 1 × 6 × 8 ÷ 12 = 4 board feet. Ten of them make 40 board feet.
Worked example
These are the calculator’s starting values and the results they produce:
| Thickness | 1 in |
|---|---|
| Width | 6 in |
| Length | 8 ft |
| Number of boards | 10 |
| Price per board foot | $5.00 |
Tips before you buy
- Hardwood is priced on rough (pre-planed) dimensions; your finished boards will be thinner and narrower.
- Add 20–30% to your cut list’s board feet for defects, planing and offcuts when buying rough lumber.
- Softwood dimensional lumber (2×4s, 2×6s) is usually sold per piece or per linear foot, and its board-foot volume uses nominal sizes.
- Wood should be dry (6–8% moisture content for indoor furniture) before you build.
Frequently asked questions
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. A 2 in × 8 in board 10 ft long is 2 × 8 × 10 ÷ 12 = 13.33 board feet.
How many board feet are in a 2×4×8?
Using nominal dimensions, a 2×4 that is 8 ft long has 2 × 4 × 8 ÷ 12 = 5.33 board feet.
What is 4/4 lumber?
Four-quarter (4/4) lumber is rough-sawn hardwood 1 in thick. 5/4 is 1¼ in, 6/4 is 1½ in and 8/4 is 2 in. After surfacing, 4/4 boards typically finish at about ¾ in.
How do I convert linear feet to board feet?
Multiply the linear feet by the board’s thickness and width in inches, then divide by 12. Twenty linear feet of 1 × 6 in lumber is 20 × 1 × 6 ÷ 12 = 10 board feet.
Sources
Areas and volumes are standard geometry. The published figures this calculator relies on come from these sources; other defaults (waste allowances, typical densities and prices) are common trade figures worth checking with your supplier.
- USDA Forest Products Laboratory, Wood Handbook (FPL-GTR-282): the board foot: 144 cubic inches, priced on nominal (rough) sizes
- NIST PS 20-25, American Softwood Lumber Standard: nominal vs. dressed sizes of softwood lumber (a 2×4 is 1½ × 3½ in)