How it works
A board foot is a unit of volume, not of length: 144 cubic inches, the volume of a piece one inch thick, twelve inches wide and twelve inches long. From thickness in inches, width in inches, length in feet and a quantity, the standard hand rule is thickness × width × length(ft) ÷ 12. The page keeps a running total for the whole list and reports board feet, linear feet, cubic metres at 0.002360 m³ per board foot, and total cost at your dollars-per-board-foot rate.
Each row carries its own species, dimensions, quantity and price. Choosing a species overwrites that row's price with a preset — SPF (2-by) at 1.80, Pine 2.50, Cedar 4.00, Maple 6.50, Oak 7.00, Cherry 9.00, Mahogany 11.00, Walnut 12.00 — and you can type over it immediately. The Lumber size selector names the two conventions, Actual dimensions and Nominal, but the arithmetic always uses the numbers you type, so enter planed sizes: 1.5 × 3.5 for a 2×4, 0.75 × 5.5 for a 1×6.
This is a volume and price sheet, nothing more. There is no waste, defect or kerf allowance, so a rough-sawn hardwood order usually needs 15 to 30 percent added on top for cupped boards, sapwood and cutting losses. Hardwood is normally sold in quarter thicknesses — 4/4 is one inch rough, which surfaces down to about 13/16 — and the tool cannot know which you are being charged for. Sales tax, delivery and minimum-order charges are not included.
Frequently asked questions
How many board feet are in a 2x4 that is 8 feet long? +
Using the planed actual size of 1.5 by 3.5 inches, it is 1.5 × 3.5 × 8 ÷ 12, which is 3.5 board feet. Entering the nominal 2 by 4 instead would give 5.33 board feet, which is why planed dimensions matter.
What is the difference between board feet and linear feet? +
Linear feet just counts length and ignores how thick or wide the stock is. Board feet is volume. The result panel shows both, because lumber yards price hardwood by the board foot but sell dimensional softwood and trim by the piece or linear foot.
Should I enter nominal or actual lumber dimensions? +
Enter actual, planed dimensions. A 2x4 measures 1.5 by 3.5 inches, a 1x6 measures 0.75 by 5.5 inches, and a 4x4 measures 3.5 by 3.5 inches. Nominal names describe the rough size before drying and surfacing, and overstate volume noticeably.
How do I convert board feet to cubic metres? +
The tool does it for you using 1 board foot equal to 0.002360 cubic metres, shown next to the total. If you enter metric instead, switch Units and type thickness and width in millimetres and length in metres; they convert at 25.4 and 3.28084.
Can I price several different species in one list? +
Yes. Add a row per species with the + Add row button; each row keeps its own dollars-per-board-foot price, and the detail table breaks out board feet and cost line by line while the summary shows the combined total for the whole order.
Nominal against actual, and which one the formula uses
Board footage is calculated from nominal dimensions — the size lumber is sold as, not the size it measures. A "2×4" is about 1.5 by 3.5 inches after surfacing, roughly 0.75 of its nominal thickness in each direction, and the tool works in nominal because that is how lumber is priced.
The consequence is that board feet will never match a tape measure, and that is correct rather than an error. You are buying a nominal quantity and receiving a dressed one.
Rough sawn, quarters, and buying for a project
Rough-sawn hardwood is different again: it is sold in quarter-inch thicknesses — 4/4, 5/4, 8/4 — and measured at full nominal thickness because it has not been surfaced. Surfacing it yourself removes material, so 4/4 rough yields something closer to 13/16 dressed.
Hardwood is also sold in random widths and lengths rather than dimensioned stock, so the board footage you need and the board footage you can buy are different numbers. Budget 20–30% over the calculated figure for a project with specific dimensions, more if the grain or colour has to match across pieces.
