🪵 Board Foot Calculator
Calculate board feet for one board or a whole lumber list, with 4/4–16/4 thicknesses, price per board foot, a waste allowance and cubic volume.
Use the dimensions your supplier prices by: hardwood dealers usually quote rough thickness in quarters, while dimensional softwood is often counted at nominal size (a 2×4 as 2 × 4 inches, though it measures about 1½ × 3½).
What Board Foot Calculator Does
This board foot calculator works out how much lumber you are buying in board feet — the unit hardwood dealers and many sawmills price by. Enter each board’s quantity, thickness, width and length, and add as many boards as your cut list needs. Thickness can be typed as a decimal, a fraction such as 1 1/2, or in lumberyard quarters such as 8/4.
Each board shows its board feet and cost, and the total adds a waste allowance for knots, checks and saw kerf so you buy enough. The result also gives linear feet, cubic feet and cubic meters — handy when a supplier quotes by volume or when you are estimating weight or shipping.
How to Use Board Foot Calculator
- Enter each board’s quantity, thickness, width and length
- Type thickness as decimals, fractions or quarters like 8/4
- Add more boards for a full cut list
- Enter the price per board foot and a waste allowance
- Read the total board feet, cost and volume
Formula Used by Board Foot Calculator
Board feet
BF = thickness (in) × width (in) × length (ft) ÷ 12 · or, with length in inches, ÷ 144
Worked example
The sample list: four 8/4 × 6″ × 8′ boards, ten 4/4 × 8″ × 10′ boards and six 2×4s 8′ long, at $6.50 per board foot.
- 4 × (2 × 6 × 8 ÷ 12) = 32 BF
- 10 × (1 × 8 × 10 ÷ 12) = 66.67 BF
- 6 × (2 × 4 × 8 ÷ 12) = 32 BF
Result: 130.67 BF, or $849.33; with 15% waste, 150.27 BF.
Board Feet by Nominal Size
| Nominal size | BF per foot | 8 ft | 10 ft | 12 ft |
|---|---|---|---|---|
| 1×4 | 0.333 | 2.67 | 3.33 | 4 |
| 1×6 | 0.5 | 4 | 5 | 6 |
| 1×8 | 0.667 | 5.33 | 6.67 | 8 |
| 2×4 | 0.667 | 5.33 | 6.67 | 8 |
| 2×6 | 1 | 8 | 10 | 12 |
| 2×8 | 1.333 | 10.67 | 13.33 | 16 |
| 2×10 | 1.667 | 13.33 | 16.67 | 20 |
| 4×4 | 1.333 | 10.67 | 13.33 | 16 |
Hardwood Thickness in Quarters
| Quarters | Rough thickness | Typical thickness surfaced two sides |
|---|---|---|
| 4/4 | 1″ | 13/16″ |
| 5/4 | 1¼″ | 1 1/16″ |
| 6/4 | 1½″ | 1 5/16″ |
| 8/4 | 2″ | 1¾″ |
| 12/4 | 3″ | 2¾″ |
| 16/4 | 4″ | 3¾″ |
How to Read Your Result
Nominal or actual size?
Softwood construction lumber is named by nominal size — a 2×4 measures about 1½ × 3½ inches after drying and planing — and its board feet are usually counted at the nominal size. Hardwood is sold by rough thickness in quarters and ends up thinner once surfaced. Use whichever dimensions your supplier uses so your total matches the invoice.
Planning for waste
Work out your cut list first, then add an allowance. Boards rarely come in the exact lengths you need, ends are often checked (split), and matching grain and color for a tabletop can mean rejecting pieces. Allowances of 15–30% are common for furniture; framing with dimensional lumber needs less.
Comparing prices
To compare suppliers, convert every quote to a price per board foot. A board priced by the piece or by the linear foot converts easily: divide its price by the board feet in the piece, which this calculator shows for each row.
Limitations & Accuracy Notes
- Log scale rules (Doyle, Scribner, International ¼-inch), which estimate the lumber in a log or standing tree, are not covered.
- Live-edge slabs and irregular boards need an average width; the result is only as good as that estimate.
- Prices and waste allowances are your inputs; the calculator does not know local lumber prices.