Find out how many board feet are in a board — or a whole cut list — before you pay for it. Pick a nominal lumber size (2×4, 2×6, 4×4…) or enter your own dimensions; the formula is shown with every result so you can check the math. Free, instant, runs in your browser.
| Board | Dimensions used | Qty | Board feet | Est. cost | |
|---|---|---|---|---|---|
| Total | 0 | — | |||
A board foot is a unit of volume: 144 cubic inches (a board 1″ thick × 12″ wide × 12″ long). Estimates are for planning — real boards vary, and yards round their tallies their own way, so buy a little extra.
Multiply thickness (inches) × width (inches) × length (feet), then divide by 12. If you measure the length in inches instead, divide by 144 — same answer.
Board feet = T(in) × W(in) × L(ft) ÷ 12
Worked example: one nominal 2×4, 8 ft long → (2 × 4 × 8) ÷ 12 = 5.33 board feet. Ten of them: 5.33 × 10 = 53.3 BF. At $9 per board foot, that is about $480.
A "2×4" is sawn at 2 × 4 inches, then dried and planed — the finished board measures about 1½ × 3½ inches. That is why the name and the tape measure disagree. Board footage for dimensional softwood is tallied on the nominal size (2 × 4, not 1½ × 3½), the way lumberyards count it — so this calculator does the same when you pick a nominal size. The actual sizes are shown for reference when you build.
| Nominal size | Actual size (in) | Actual size (mm) |
|---|---|---|
| 1 × 2 | ¾ × 1½ | 19 × 38 |
| 1 × 4 | ¾ × 3½ | 19 × 89 |
| 1 × 6 | ¾ × 5½ | 19 × 140 |
| 1 × 8 | ¾ × 7¼ | 19 × 184 |
| 1 × 10 | ¾ × 9¼ | 19 × 235 |
| 1 × 12 | ¾ × 11¼ | 19 × 286 |
| 2 × 4 | 1½ × 3½ | 38 × 89 |
| 2 × 6 | 1½ × 5½ | 38 × 140 |
| 2 × 8 | 1½ × 7¼ | 38 × 184 |
| 2 × 10 | 1½ × 9¼ | 38 × 235 |
| 2 × 12 | 1½ × 11¼ | 38 × 286 |
| 4 × 4 | 3½ × 3½ | 89 × 89 |
| 4 × 6 | 3½ × 5½ | 89 × 140 |
| 6 × 6 | 5½ × 5½ | 140 × 140 |
Standard finished (surfaced) sizes for North American dimensional softwood. The pattern: 1× stock is ¾″ thick, 2× is 1½″ thick; widths lose ½″ up to 6″ nominal and ¾″ from 8″ up.
One board foot (BF) is 144 cubic inches of wood — the volume of a board 1 inch thick, 12 inches wide and 12 inches long. It measures volume, not area, which is why it is the unit hardwood dealers price by: a wide board and a narrow board of the same length contain different amounts of wood. In metric terms, 1 BF ≈ 2,360 cm³, and 1 cubic metre ≈ 424 board feet. A thousand board feet is written MBF.
Because that is how the trade counts it. Dimensional softwood is sold and tallied on its nominal size, so a 2×4 × 8 ft is 5.33 BF at the yard — even though the finished board is smaller. If you are buying hardwood, it is sold rough and tallied on its actual (quarter-system) thickness, so use "Custom dimensions" and enter what you measure.
Hardwood thickness is sold in quarters of an inch: 4/4 ("four-quarter") is 1″, 5/4 is 1¼″, 6/4 is 1½″, 8/4 is 2″ and 12/4 is 3″. The tally uses the rough quarter thickness, before surfacing.
A board foot is volume (thickness × width × length) — used for hardwood and rough lumber. A square foot is area — used for flooring, plywood and sheet goods. A linear foot is length only — used for trim, molding and some dimensional lumber sold by the piece.
Add every board to the cut list, enter the price per board foot your yard quotes (hardwood is usually quoted this way), and the total cost updates itself. Add 10–15% extra board feet for waste, miscuts and defects — the most common reason DIYers run short mid-project.