Board Foot Calculator
Hardwood is bought and sold by the board foot — the volume of a board 1 inch thick, 12 inches wide, and 12 inches long (144 cubic inches). This board foot calculator applies the standard formula to your board’s thickness, width, length, and quantity, then shows the equivalent cubic footage and an estimated weight for pine, oak, or walnut. It is the quick conversion sawyers, woodworkers, and buyers use to price rough lumber.
Nominal thickness in inches (e.g. 4/4 = 1 in).
Nominal width in inches.
Board length in feet.
Number of identical boards.
Dry-lumber weight is a rule-of-thumb estimate.
Board feet
8bf
- Cubic feet
- 0.667ft³
- Estimated weightDry lumber, rule of thumb
- 28lb
How it was calculated
- Board feet = (2.00 × 6.00 × 8.0) ÷ 12 × 1 = 8.00 bf
- Cubic feet = 8.00 ÷ 12 = 0.667 ft³
- Weight = 8.00 × 3.5 lb/bf = 28.0 lb (pine)
How it works
One board foot is 144 cubic inches — a board 1 in thick × 12 in wide × 12 in long. The formula folds those units together: board feet = (thickness in inches × width in inches × length in feet) ÷ 12. Length stays in feet because 12 inches of length is already baked into the divisor.
The lumber trade prices rough stock on nominal dimensions — a “2×6” is counted as 2 in × 6 in even though the surfaced board is smaller. Always run the formula on nominal sizes when comparing quotes, since that is what the yard charges for.
Cubic feet is a straight conversion: 12 board feet make exactly 1 cubic foot, so cubic feet = board feet ÷ 12.
Weight is board feet × the species’ dry weight per board foot — about 3.5 lb for pine, 4.5 lb for oak, and 4.0 lb for walnut as rules of thumb. Green or air-dried stock can weigh substantially more, so treat the figure as a hauling and handling estimate.
Worked examples
A single 2×6×8 pine board
Thickness 2 in, width 6 in, length 8 ft, quantity 1: board feet = (2 × 6 × 8) ÷ 12 = 8 bf. That is 8 ÷ 12 = 0.667 ft³, and at 3.5 lb per board foot the pine board weighs about 28 lb.
Five 1×12×10 oak boards
Thickness 1 in, width 12 in, length 10 ft, quantity 5: one board = (1 × 12 × 10) ÷ 12 = 10 bf, so five boards = 50 bf. Cubic volume = 50 ÷ 12 = 4.167 ft³, and oak at 4.5 lb per board foot puts the stack at roughly 225 lb — plan help or a cart for loading.
How to measure
- Use nominal dimensions (the 2×4 name), not the smaller actual surfaced size — lumber is priced on nominal.
- Measure thickness and width in inches and length in feet, matching how yards quote stock; the formula expects exactly that mix.
- Hardwood thickness is often quoted in quarters — 4/4 means 1 in, 8/4 means 2 in — so translate before entering.
- Count boards by identical size; run a separate calculation for each size in the pile rather than averaging.
- Separate species before calculating — pine and oak differ by nearly 30% in weight per board foot.
- For random-width hardwood sold by the board foot, measure each board’s average width and enter boards individually for an honest total.
Assumptions & limitations
Planning estimate
- Board-foot math uses nominal dimensions as a rule of thumb of the lumber trade; surfaced boards are physically smaller.
- Species weights (pine 3.5, oak 4.5, walnut 4.0 lb per board foot) are rules of thumb for dry lumber, not certified densities.
- Weight is a handling estimate — green, wet, or dense old-growth stock can weigh far more than the dry figure shown.
- The calculation assumes rectangular boards; live-edge slabs with heavy wane need width averaging for an honest result.
- Quantity multiplies identical boards exactly — mixed lengths should be calculated as separate line items.
Frequently asked questions
A board foot is 144 cubic inches of lumber — the volume of a board 1 inch thick, 12 inches wide, and 12 inches long. It is the standard unit for pricing hardwood and rough-sawn softwood in North America. Softwood framing lumber at the home center is usually priced per piece instead, but anything from a sawmill is quoted per board foot.
Because length is entered in feet while thickness and width are in inches. Multiplying T(in) × W(in) × L(ft) gives inch-inch-foot units; dividing by 12 converts the foot of length into the 12 inches that complete the 144-cubic-inch board foot. The division is the unit conversion, not a fudge factor.
Nominal — the name on the price tag. A 2×6 is counted as 2 × 6 in the board-foot formula even though it actually measures 1.5 × 5.5 in. Yards price and sell on nominal sizes, so using actual dimensions would undercount what you pay for. The one exception is buying rough-sawn direct from a mill, where boards are closer to full size.
Roughly 4.5 lb per board foot for dry red or white oak — the rule-of-thumb figure this calculator uses. Pine runs about 3.5 lb and walnut about 4.0 lb. Fresh-sawn green oak can exceed 6 lb per board foot, so if you are hauling green lumber, budget well above the dry estimate.
Using nominal dimensions: (2 × 4 × 8) ÷ 12 = 5.33 board feet. Framing lumber is rarely sold by the board foot at retail — you will see a per-stud price — but the conversion is handy when comparing a stud price against bulk rough-lumber quotes.