Deck & Fence
Board Foot Calculator
Calculate board feet for any lumber list. Enter the thickness, width, length and number of pieces for each row, and this board foot calculator totals the board footage, adds an allowance for defects and gives the cost at your price per board foot.
Result
Enter your measurements and press Calculate. What to buy, the working and the cost will appear here.
What is a board foot?
A board foot is a volume of wood: 12 in × 12 in × 1 in, or 144 cubic inches. Hardwood lumber, and some softwood, is priced per board foot because boards come in random widths and lengths. A board 1 in thick, 12 in wide and 1 ft long is one board foot; so is a board 2 in thick, 6 in wide and 1 ft long.
Board foot formula
board feet = thickness (in) × width (in) × length (ft) ÷ 12
A 1 × 6 board 8 ft long is 1 × 6 × 8 ÷ 12 = 4 board feet. If all three dimensions are in inches, divide by 144 instead.
How to use the board foot calculator
- Add a row for each size of board: thickness, width, length and number of pieces.
- Use rough thickness for hardwood: 4/4 stock is counted as 1 in, 8/4 as 2 in, even though it planes thinner.
- Set the allowance for defects and milling waste, add the price per board foot, and press Calculate.
Worked example: a hardwood order
Ten 4/4 boards 6 in wide and 8 ft long, plus four 8/4 boards 8 in wide and 6 ft long, at $6.50 per board foot with 15% extra:
- Row 1: 1 in × 6 in × 8 ft ÷ 12 = 4 × 10 = 40
- Row 2: 2 in × 8 in × 6 ft ÷ 12 = 8 × 4 = 32
Board feet: 72 bd ft; With 15% extra: 82.8 bd ft; Volume: 6 ft³; Estimated cost: $538.20. Open this example in the calculator.
Hardwood thickness in quarters
| Quarter | Rough thickness | Typical surfaced |
|---|---|---|
| 4/4 | 1 in | 13/16–3/4 in |
| 5/4 | 1 1/4 in | 1 1/16 in |
| 6/4 | 1 1/2 in | 1 5/16 in |
| 8/4 | 2 in | 1 3/4 in |
Board feet, linear feet and square feet
- Board feet measure volume, used for hardwood and rough lumber.
- Linear feet measure length only, used for dimensional lumber, trim and moldings; see the linear feet calculator.
- Square feet measure area, used for plywood, flooring and decking.
Assumptions and limitations
- Board feet are calculated from the dimensions you enter, so use nominal rough sizes when buying hardwood.
- The allowance covers knots, checks, end trimming and planing waste; figure is often 15–30% for hardwood projects.
Board foot questions
How many board feet in a 2 × 4 × 8?
Using nominal size, 2 × 4 × 8 ÷ 12 = 5.33 board feet.
How do I calculate board feet in inches?
Multiply thickness × width × length, all in inches, and divide by 144.
How many board feet are in a cubic foot?
12. A cubic foot is 1,728 in³ and a board foot 144 in³.
Formulas, unit conversions and default values are explained on our methodology page. Results are estimates; check manufacturer data and local codes before you buy or build.