How do I calculate the cost of lumber?

Multiply the total board-feet by the price per board-foot. Enter the price in the Price/BF column and the calculator will compute the cost automatically.

Why does my lumber measure differently than the nominal size?

Lumber is sold by nominal dimensions (e.g., 2×4) but actual dimensions are smaller after drying and planing (e.g., 1.5×3.5 in). For board-foot billing, suppliers typically use the nominal size. Use the nominal size in this calculator unless your supplier specifies otherwise.

How is the weight calculated?

Weight is estimated from the wood volume × the average dry density of the selected species. Actual weight varies with moisture content - green (wet) wood can weigh twice as much.

Lumber Calculator - Board-Foot Calculator Online

Label

T (in)

W (in)

L (ft)

Qty

$/BF

Cost

Wt (lbs)

53.33

$80.00

163.7

40.00

$80.00

122.8

Totals

93.33

$160.00

286.5

What is a board-foot?

A board-foot (BF) is the standard unit for measuring lumber volume in the United States. One board-foot equals a piece of wood 1 inch thick, 12 inches wide, and 1 foot long. The formula is:

Board-Feet = (Thickness × Width × Length) / 12

where thickness and width are in inches and length is in feet.

Nominal vs. actual dimensions

Lumber is sold by nominal dimensions (e.g., 2×4, 2×6) but its actual milled dimensions are smaller. A nominal 2×4 measures approximately 1.5 × 3.5 inches. Lumber suppliers typically bill by nominal dimensions for board-feet, so use nominal sizes in this calculator unless your supplier specifies otherwise.

Nominal size	Actual size (dry)
1×2	3/4” × 1-1/2”
1×4	3/4” × 3-1/2”
1×6	3/4” × 5-1/2”
2×4	1-1/2” × 3-1/2”
2×6	1-1/2” × 5-1/2”
2×8	1-1/2” × 7-1/4”
2×10	1-1/2” × 9-1/4”
2×12	1-1/2” × 11-1/4”
4×4	3-1/2” × 3-1/2”

Common lumber grades

#1 (Construction grade): tight knots, minimal defects; used for structural framing, headers, beams.
#2 (Standard grade): slightly more defects; the most common framing lumber for walls, floors, and roofs.
S4S (Surfaced four sides): smooth on all four faces; used for trim, shelving, furniture.
Common board: lower cost, used for non-structural applications like fencing, crates, and decorative projects.

Weight estimation

Weight is estimated by multiplying the wood volume by the average air-dry density of the selected species. Green (wet) lumber can weigh 50–100% more. Use the weight estimate for planning transport, not structural calculations.

Treatment and preservation

Pressure-treated (PT): lumber impregnated with preservatives under pressure. Required for any wood in contact with ground, concrete, or in wet locations (decks, fence posts, sill plates). Modern PT uses copper-based compounds (CA-C, ACQ).
Heat-treated (HT): lumber heated to at least 56°C to eliminate insects and pathogens. Required by IPPC regulations for wood packaging and pallets in international trade (marked with the IPPC symbol).
Kiln-dried (KD): lumber dried in a controlled oven to a target moisture content (typically 15–19%). KD lumber is more dimensionally stable, lighter, and accepts paint/stain better than green lumber. Look for "KD-HT" stamps for both treatments.

Engineered lumber

Modern construction often uses engineered lumber products that are not measured in board-feet:

LVL (Laminated Veneer Lumber): thin veneers glued with grain aligned in one direction - produces very strong, consistent beams used for headers, ridge beams, and long-span applications.
I-joists: engineered floor and roof joists with an OSB web and LVL flanges. Lighter, straighter, and longer-spanning than dimensional lumber joists.
OSB (Oriented Strand Board): wood strands layered in alternating directions and glued. Used for wall, roof, and floor sheathing - largely replaced plywood in new construction.
Plywood: thin wood veneers glued in alternating grain directions. Stiffer and more moisture-resistant than OSB at equal thickness; still preferred for many structural and finish applications.