Calculate total board feet of lumber for an order. Board feet is the standard pricing unit for rough and dimensional lumber.
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Estimated cost
Usage Tip
Hardwood is often sold in quarters of an inch (4/4 is 1 inch rough); ask whether the price is for rough or surfaced stock.
total = board feet per piece × quantity
Use actual dimensions for accuracy; a 2x6 is really 1.5 by 5.5 inches.
How much lumber do I need?
Pick the size and length, enter how many pieces, and this calculator returns the figures every lumber order needs: linear feet, board feet, face square footage, cubic volume, weight and cost. It also shows the truth nobody tells you at the register — that a 2x4 is not 2 by 4 — so your project measurements actually match the wood you carry home.
Nominal vs actual lumber size
Softwood is named by its rough-sawn size before it is dried and planed smooth. The finished board you buy is smaller. Plan with the actual size; order with the nominal name.
| Nominal | Actual (dressed) |
|---|---|
| 1x4 | 3/4 x 3-1/2 in |
| 1x6 | 3/4 x 5-1/2 in |
| 2x4 | 1-1/2 x 3-1/2 in |
| 2x6 | 1-1/2 x 5-1/2 in |
| 2x8 | 1-1/2 x 7-1/4 in |
| 2x10 | 1-1/2 x 9-1/4 in |
| 2x12 | 1-1/2 x 11-1/4 in |
| 4x4 | 3-1/2 x 3-1/2 in |
Boards under 2 in nominal lose 1/4 in; 2 in stock loses 1/2 in thickness; widths lose 1/2 in up to 7 in nominal and 3/4 in at 8 in and wider. Rough-sawn lumber keeps its full nominal size.
Board foot formula
A board foot is the volume of a piece 1 in thick, 12 in wide and 1 ft long. It is calculated from the nominal dimensions:
Board feet = nominal thickness (in) × nominal width (in) × length (ft) ÷ 12
So a 2x8 that is 12 ft long is (2 × 8 × 12) ÷ 12 = 16 board feet. Hardwood is almost always priced by the board foot, which is why the figure matters.
Common lumber sizes and uses
| Size | Typical use |
|---|---|
| 2x4 | Wall framing, studs |
| 2x6 | Walls, rafters, decking |
| 2x8 to 2x12 | Joists, beams, stair stringers |
| 4x4 / 6x6 | Posts |
| 5/4x6 | Deck boards |
| 1x4 to 1x12 | Trim, shelving, fencing |
Project examples
Framing
A 12 ft wall with studs at 16 in on center needs about 10 studs plus plates — roughly twelve 2x4x8s, or about 64 board feet before waste.
Decking
A 12 by 16 ft deck in 5/4x6 takes around 42 boards; estimate board feet and weight here, then confirm the layout in the deck calculator.
Fencing
100 ft of 6 ft privacy fence in 1x6 is about 219 pickets; this tool gives the linear and board feet, and the fence calculator handles posts and rails.
Weight, species and treatment
Weight depends on species and moisture. Dry softwood pine runs about 28 lb per cubic foot, cedar lighter at 23, Douglas fir near 32, and oak much heavier near 47. Green lumber can weigh a third more, and pressure-treated stock is heaviest of all because it is both wet and chemically loaded. The weight estimate matters for transport and for sizing the help you call.
Frequently asked questions
Why is a 2x4 not actually 2 by 4 inches?
The nominal size is the rough green dimension. After drying and planing smooth, a 2x4 finishes at 1-1/2 by 3-1/2 in.
How do I calculate board feet?
Multiply nominal thickness by nominal width in inches by the length in feet, then divide by 12. A 1x12x10 is 10 board feet.
Linear feet or board feet — which do I use?
Linear feet count length only and suit framing and trim sold by the piece. Board feet account for thickness and width and are used to price hardwood and rough lumber.
Does rough lumber use the same sizes?
No. Rough-sawn lumber keeps close to its full nominal size, so a rough 1 in board really is about 1 in thick.
How much waste should I add?
About 10 percent for straight cuts, 15 percent or more for angled or complex work and for picking around defects.
How much does lumber weigh?
A dry 2x4x8 is roughly 9 lb; the same board green or treated can be 15 lb or more. The calculator estimates from species and condition.
Board Foot Calculator · Cut List Calculator · Project Cost Calculator · Fence Board Calculator · Waste Factor Calculator
Estimates are for planning. Actual dimensions, species density and moisture vary by mill and region; weigh and measure a sample where precision matters, and confirm quantities before purchase.