Board Foot Lumber Calculator
Enter the board size and quantity — the calculator converts to board feet, the unit hardwood (and many mills) price by.
Runs entirely in your browser — your numbers never leave this page.
How it works
A board foot is the lumber industry's volume unit: a piece 1 inch thick × 12 inches wide × 1 foot long. Hardwood dealers and sawmills price by it, so converting your cut list to board feet is how you compare quotes:
Board feet (one board) = Thickness (in) × Width (in) × Length (ft) ÷ 12
Total board feet = Board feet per board × Number of boards
- Nominal, not actual: a "2×6" is really 1.5 × 5.5 inches, but board feet are figured on the nominal 2 × 6 — a 2×6×8 is exactly 8 board feet.
- Quick checks: a 1×6×8 = 4 BF, a 2×4×8 = 5.33 BF, a 4×4×8 = 10.67 BF.
- Thickness shortcut: 4/4 lumber = 1 in, 5/4 = 1.25 in, 8/4 = 2 in — hardwood dealers quote thickness in "quarters."
- Add 15–30% waste when buying rough hardwood — you'll lose width jointing edges and thickness planing flat.
- Metric note: 1 board foot ≈ 0.00236 cubic meters (about 2.36 liters of wood).
Frequently asked questions
What is a board foot, exactly?
A volume of wood 1 inch thick × 12 inches wide × 1 foot long (144 cubic inches). It lets you compare the price of any board size on equal footing — the standard pricing unit for hardwood and mill lumber.
Do I use nominal or actual dimensions?
Nominal. Board feet are always figured on the named size: a 2×4 counts as 2 in × 4 in even though it actually measures 1.5 × 3.5 in. So a 2×4×8 = 5.33 board feet.
How many board feet are in a 2×4×8?
5.33 BF. (2 × 4 × 8) ÷ 12 = 5.33. A 2×6×8 is 8 BF, and a 1×6×8 is 4 BF.
Why is hardwood sold by the board foot but 2×4s are sold by the piece?
Construction lumber comes in fixed standard sizes, so per-piece pricing is simpler. Hardwood comes in random widths and lengths from the mill, so the board foot is the only fair way to price odd sizes.
What does 4/4 or 8/4 mean?
Hardwood thickness in quarters of an inch: 4/4 = 1 in, 5/4 = 1.25 in, 6/4 = 1.5 in, 8/4 = 2 in. It describes the rough-sawn thickness before planing.
How much waste should I add when buying lumber?
For rough hardwood, add 15–30% — planing, jointing, and cutting around defects eats real wood. For surfaced (S4S) boards in a simple project, 10% is usually enough.
Board feet vs linear feet — what is the difference?
A linear foot is just length (an 8-ft board = 8 linear ft regardless of size). A board foot includes thickness and width, so it measures actual wood volume — that is why it is used for pricing.
How do I convert board feet to cubic meters?
Multiply by 0.00236. So 100 board feet ≈ 0.236 cubic meters. One board foot is about 2.36 liters of wood.
The price field is optional — what if I skip it?
You still get the full board-foot math; the cost row just doesn't appear. Enter a per-board-foot price any time to see the estimated total.
Why do two boards with the same board feet cost different amounts?
Species, grade, and figure drive price more than volume. A board foot of plain red oak might be $4 while figured walnut is $15+ — same math, very different wood.