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Add up every board in your project, include a waste allowance and get total board feet, cubic feet and cost. Works with inches, feet, millimeters and meters, and converts linear feet to board feet too.
Quick answer: Board feet = thickness (in) × width (in) × length (ft) ÷ 12. One board foot is a piece 1 inch thick, 12 inches wide and 12 inches long, which is 144 cubic inches, or 1/12 of a cubic foot.
Multiply the result by the number of pieces for a stack of identical boards. Lumber sold by the board foot, mostly hardwood, is priced this way because it compares boards of different sizes fairly.
2 × 6 × 8 ÷ 12 = 8 board feet.
1 × 8 × 10 ÷ 12 = 6.67 board feet. Ten of them are 66.7 board feet.
The volume is 0.025 × 0.15 × 3 = 0.01125 m³. One board foot is 0.0023597 m³, so the piece is about 4.77 board feet.
You need 120 board feet of oak at $6.25 per board foot, with 15% waste. 120 × 1.15 = 138 board feet to buy. 138 × $6.25 = $862.50.
100 linear feet of 2×4 is 100 × 2 × 4 ÷ 12 = 66.67 board feet. Use the second tab of the calculator to run this either way.
Nominal sizes in inches, rounded to two decimals. Multiply by the number of pieces.
| Nominal size | 8 ft | 10 ft | 12 ft | 16 ft |
|---|---|---|---|---|
| 1 × 4 | 2.67 | 3.33 | 4.00 | 5.33 |
| 1 × 6 | 4.00 | 5.00 | 6.00 | 8.00 |
| 1 × 8 | 5.33 | 6.67 | 8.00 | 10.67 |
| 1 × 10 | 6.67 | 8.33 | 10.00 | 13.33 |
| 1 × 12 | 8.00 | 10.00 | 12.00 | 16.00 |
| 2 × 4 | 5.33 | 6.67 | 8.00 | 10.67 |
| 2 × 6 | 8.00 | 10.00 | 12.00 | 16.00 |
| 2 × 8 | 10.67 | 13.33 | 16.00 | 21.33 |
| 2 × 10 | 13.33 | 16.67 | 20.00 | 26.67 |
| 2 × 12 | 16.00 | 20.00 | 24.00 | 32.00 |
| 4 × 4 | 10.67 | 13.33 | 16.00 | 21.33 |
| 4 × 6 | 16.00 | 20.00 | 24.00 | 32.00 |
| 6 × 6 | 24.00 | 30.00 | 36.00 | 48.00 |
Board feet are calculated from the nominal (named) size for dimensional lumber. A “2×4” is really about 1½ × 3½ inches after drying and planing, but it is sold and priced as 2 × 4. For rough-sawn hardwood the quarter system is used instead: 4/4 means 1 inch, 5/4 is 1¼ inch, 6/4 is 1½ inch, 8/4 is 2 inches, and so on. These are rough thicknesses before the board is planed. If you buy surfaced boards (S2S or S4S), the supplier still usually prices from the rough thickness. Always ask which they use.
| Board feet | Cubic feet | Cubic meters | Cubic inches |
|---|---|---|---|
| 1 | 0.0833 | 0.00236 | 144 |
| 12 | 1 | 0.02832 | 1,728 |
| 50 | 4.167 | 0.1180 | 7,200 |
| 100 | 8.333 | 0.2360 | 14,400 |
| 424 (about 1 m³) | 35.33 | 1 | 61,056 |
A board foot is a unit of lumber volume equal to a piece 1 inch thick, 12 inches wide and 12 inches long, or 144 cubic inches. Twelve board feet make one cubic foot.
Multiply thickness in inches by width in inches by length in feet, then divide by 12. For a 2 × 6 that is 8 feet long: 2 × 6 × 8 ÷ 12 = 8 board feet.
A 2×4×8 contains 5.33 board feet (2 × 4 × 8 ÷ 12). A 2×4×10 has 6.67 and a 2×4×12 has 8.
A 1×6×8 contains 4 board feet (1 × 6 × 8 ÷ 12).
Multiply the linear feet by thickness in inches and width in inches, then divide by 12. For example, 50 linear feet of 1 × 6 is 50 × 1 × 6 ÷ 12 = 25 board feet.
They are rough-lumber thicknesses in quarters of an inch: 4/4 is 1 inch, 5/4 is 1¼ inches, 6/4 is 1½ inches and 8/4 is 2 inches.
Use the nominal size the lumber is sold as, such as 2 × 4. Mills and lumberyards price dimensional lumber on the nominal size even though the finished piece is smaller.
About 5% for straight framing lumber, 10–15% for most furniture and cabinet projects, and 20% or more when you want clear, matched or figured boards.
There are 12 board feet in one cubic foot, and one board foot equals about 0.0833 cubic feet or 0.00236 cubic meters.
Convert millimeters to inches (divide by 25.4) and meters to feet (divide by 0.3048), then use the standard formula. This calculator does it automatically when you choose the millimeters and meters option.
The board foot is defined as 144 cubic inches (1 in × 12 in × 12 in); metric conversions use 1 inch = 25.4 mm exactly, per NIST Special Publication 811. Every worked example and table value on this page was recalculated against the formula shown. Prices and yields vary by species, grade and supplier, so confirm quantities with your lumberyard. See our editorial policy for how we build and review tools.