How to use this calculator
- Enter board dimensions. Use actual thickness, width and length for the lumber being bought or tallied.
- Enter quantity. Set the number of identical boards.
- Add waste and price. Use waste for defects, trimming and kerf, then enter price per board foot if you want a cost estimate.
- Choose species if weight matters. Select a species preset or custom density for a rough payload or handling weight.
- Read board feet, cost and weight. Review total board feet, net volume, waste allowance, estimated lumber cost and buy-weight.
How it works
A board foot is a lumber volume unit equal to one square foot of board that is one inch thick. The standard formula is: board feet = T(in) x W(in) x L(ft) / 12 The calculator multiplies by quantity, then adds the waste or overage percentage before estimating cost.
Species does not change the board-foot tally. It only converts the resulting buy volume into an approximate load weight: estimated weight = total board feet x 144 in^3/bd ft x density Use this weight as a screening number for handling, pickup payload, rack loading or shipping. For a dedicated payload workflow, use the lumber weight calculator.
Board Feet Chart
Use this quick chart for one board at 1 in tally thickness
before waste. It is useful for rough lumber estimates, but the live
calculator above is safer when the board is dressed, tapered, unusually
thick, priced by the board foot or bought in repeated quantities. The
board feet chart page gives the same lookup as
a compact reference. The board foot calculator
and lumber board foot calculator
search paths route to this same working calculator.
| Board width | 8 ft length | 10 ft length | 12 ft length |
|---|---|---|---|
| 4 in | 2.67 bd ft | 3.33 bd ft | 4 bd ft |
| 6 in | 4 bd ft | 5 bd ft | 6 bd ft |
| 8 in | 5.33 bd ft | 6.67 bd ft | 8 bd ft |
| 10 in | 6.67 bd ft | 8.33 bd ft | 10 bd ft |
| 12 in | 8 bd ft | 10 bd ft | 12 bd ft |
| Thickness convention | Multiply chart row by |
|---|---|
| 4/4 rough tally | 1.00x |
| 5/4 rough tally | 1.25x |
| 6/4 rough tally | 1.50x |
| 8/4 rough tally | 2.00x |
This is a material-tally tool, not a structural sizing tool. For metal and other stock weights, use the metal weight calculator. For stiffness or span checks, use the beam deflection calculator or LVL beam calculator.
Worked example
Verified against the live calculator
A board that is 1 in thick, 6 in wide and
8 ft long contains 1 x 6 x 8 / 12 = 4 board feet.
Ten of those boards contain 40 board feet. With a
10% waste allowance, buy 44 board feet. At
$6.25/bd ft, the estimated lumber cost is $275.
If the stock is estimated as red oak near 700 kg/m^3, the
buy-weight is about 72.7 kg, or roughly 160 lb.
Frequently asked questions
How do you calculate board feet?
Board feet = thickness in inches * width in inches * length in feet / 12. Multiply by quantity, then add any waste or overage allowance.
What does a board feet chart show?
A board feet chart is a quick lookup for common widths and lengths. It still uses the same formula, so adjust for actual thickness, dressed dimensions, quantity, waste and price before buying material.
How do I adjust a board foot chart for thicker lumber?
Board feet scale linearly with thickness. A 5/4 rough-thickness tally is 1.25 times a 4/4 row, 6/4 is 1.5 times, and 8/4 is 2 times, before any waste allowance.
Should I use nominal or actual lumber size?
Use the dimension you are buying or tallying. Hardwood and rough lumber are often sold by actual thickness and width, while construction lumber nominal sizes are smaller after dressing.
Does wood species change board feet?
No. Board feet are only volume. The species preset is used after the volume calculation to estimate load weight from density.
How many cubic feet are in a board foot?
One board foot is 144 cubic inches, or 1/12 cubic foot. It is the volume of a board 1 inch thick, 12 inches wide and 12 inches long.
Does waste include saw kerf?
Use the waste field for kerf, trimming, defects, matching grain, sorting and any overage you want to buy. For detailed cutting, use a cut list or optimizer.
Does this work with metric dimensions?
Yes. Toggle SI in the header to enter millimetres and metres; the calculator converts to the standard board-foot formula internally.
Method & assumptions
- Uses actual entered dimensions; nominal/dressed-size assumptions are not inferred.
- Waste allowance is applied after quantity, so it increases total board feet and cost.
- Species presets are approximate air-dry density values; measured density is better for payload, shipping or rack loading.
- Cost is a simple price-per-board-foot estimate before tax, surfacing, delivery or minimum-order charges.
- Defects, grade yield, live-edge slabs, taper, moisture shrinkage and cut-list optimization need separate handling.