Lumber Weight Calculator

Nominal size is the name, actual size is the board

Lumber is sold by a name that no longer matches the board. A 2x4 starts life at the sawmill close to a full 2 by 4 inches, then gives up material twice: it shrinks as it dries, and it gets planed smooth on all four sides. What leaves the yard is a board 1.5 inches thick and 3.5 inches wide. Every weight number on this page starts from that finished size, not the name on the tag.

The finished numbers are not each mill's opinion. They are fixed by Voluntary Product Standard PS 20-25, the American Softwood Lumber Standard, which NIST administers and which took effect in January 2025. The standard also splits stock by moisture: dry lumber is 19 percent moisture content or less, and unseasoned (green) lumber sits above 19 percent. Almost all lumber at a home center is stamped S-DRY or KD, so the dry columns in the table below are what you are carrying.

Use actual dimensions for weight, because weight follows the real volume of wood and water in the piece. Use nominal dimensions for board feet, because board measure is defined on the nominal cross section. That split trips people up, and it is why a 2x4 that is 8 feet long is 5.33 board feet on the receipt but only about 0.29 cubic feet of actual wood in your hands.

Weight is volume times density

Weight is volume times density, and nothing else. For a board measured in inches thick and wide with length in feet:

volume (ft³) = thickness (in) × width (in) × length (ft) × 12 ÷ 1,728

The 12 converts feet of length into inches so all three dimensions share a unit, and 1,728 is the number of cubic inches in a cubic foot. For the 2x4 that is 8 feet long: 1.5 × 3.5 × 8 × 12 ÷ 1,728 = 504 ÷ 1,728 = 0.292 ft³. That one number, multiplied by any density you like, gives the weight.

Density comes from the wood, not the board. The USDA Forest Products Laboratory's Wood handbook, FPL-GTR-282 (2021) reports each species as a specific gravity, the ratio of the wood's dry substance to water. For kiln dried lumber at 12 percent moisture content, the handbook's density relationship works out to:

density (lb/ft³) = 62.4 × specific gravity × 1.12

The 62.4 is the weight of a cubic foot of water and the 1.12 adds the mass of the 12 percent of moisture a dried board still holds. Douglas-fir has a specific gravity of 0.48, so its density is 62.4 × 0.48 × 1.12 = 33.5 lb/ft³. Multiply that by the 0.292 ft³ of our 2x4 and the board weighs 33.5 × 0.292 = 9.8 lb. Southern yellow pine, denser at 0.51, gives 62.4 × 0.51 × 1.12 = 35.6 lb/ft³ and a 10.4 lb board from the same stick of lumber.

Species: the same size, a different weight

Species is the biggest lever on the answer, bigger than any dimensional detail. Specific gravity values below come from Table 5-3 of the Wood handbook, FPL-GTR-282 (USDA Forest Products Laboratory, 2021), the standard reference for United States wood properties. Densities here are computed at 12 percent moisture content, which is kiln dried stock.

The spread is wide. A rafter-size 2x4 in western red cedar weighs 6.5 lb; the same stick in white oak weighs 14.9 lb, more than twice as much. Within a species there is range too: the handbook lists loblolly and shortleaf southern pine at 0.51 specific gravity while longleaf and slash run 0.54, and growing conditions push individual boards either side of the average. Treat these as planning numbers rather than lab certificates.

Moisture content: kiln dried versus green

Moisture is the second lever, and it works in one direction: water is heavy. Dried lumber still holds about 12 percent of its oven-dry weight in bound water, which the 1.12 factor in the density formula already covers. Green lumber, above 19 percent moisture under PS 20, holds far more. Above roughly 30 percent moisture (the fiber saturation point) the cell walls are full and extra water sits free in the cell cavities, so every added point of moisture piles on weight without adding any wood.

The effect is easy to underestimate. Take that southern yellow pine 2x4, 8 feet long, at a green 45 percent moisture content instead of 12. Converting the 0.51 specific gravity to a green-volume basis and adding the extra water lands the density near 42.7 lb/ft³, so the board weighs about 12.5 lb instead of 10.4, roughly 20 percent more. A bundle of fifty of them moves from 520 lb to about 620 lb, and nobody at the yard mentions it.

This is also why pressure treated lumber outweighs the tables: waterborne preservative arrives as water, and the board only dries back toward the 12 percent baseline after a season. Enter a higher moisture content for fresh treated stock.

Board feet: how lumber is sold

Lumber is priced and sold in board feet, a unit of volume: one board foot is 144 cubic inches, the volume of a board 1 inch thick, 12 inches wide and 12 inches long. The working formula, with nominal thickness and width in inches and length in feet, is:

board feet = nominal thickness × nominal width × length ÷ 12

Nominal dimensions are deliberate here. The lumber standard defines board measure on the nominal cross section, which is why the University of Wisconsin-Madison Extension forestry note computes a 10-foot 2x6 as 10 board feet from the name, not from the 1.5 by 5.5 board in your hand. A 2x4 that is 8 feet long is 2 × 4 × 8 ÷ 12 = 5.33 board feet. Twenty of them are 106.7 board feet, which is the number that shows up on the receipt.

The table puts volume and weight side by side for one 8-foot piece of kiln dried southern yellow pine (12 percent moisture), the heaviest common framing softwood.

Loading a pickup or a trailer

The reason most people look up lumber weight is a payload decision: will this stack fit in the truck bed, and can the truck legally carry it. Every vehicle has a payload rating on the driver's door jamb sticker, the most weight it can carry in people and cargo combined. A typical half-ton pickup lands somewhere between 1,500 and 2,000 lb, but two trucks with the same trim level can differ by several hundred pounds, so read the sticker on your truck, not a brochure average.

Work in a 1,000 lb budget, which is a safe planning number for a half-ton truck with a passenger and some tools aboard. The table converts that budget into kiln dried 2x4s, 8 feet long, by species.

Ninety-six southern pine 2x4s is 512 board feet of lumber and still fits a half-ton payload twice over. The same budget in green treated stock shrinks fast: at 45 percent moisture, 1,000 lb buys 80 boards. On a trailer the arithmetic is the same, but tongue weight is a separate check the trailer weight calculator covers.

Worked examples end to end

Example 1: a framing package of twenty Douglas-fir 2x6s, 10 feet long, kiln dried. Each board is 1.5 × 5.5 × 10 × 12 ÷ 1,728 = 0.573 ft³. Density 33.5 lb/ft³ gives 19.2 lb per board, so twenty boards weigh about 385 lb at 200 board feet total.

Example 2: deck framing, fifty western red cedar 2x8s, 12 feet long. Each board is 1.5 × 7.25 × 12 × 12 ÷ 1,728 = 0.906 ft³, and cedar's 22.4 lb/ft³ puts it at 20.3 lb, so fifty boards come to about 1,013 lb, just over the budget. Volume is 16 board feet each, 800 total.

Example 3: the moisture check. Fifty southern yellow pine 2x4s, 8 feet, bought green at 45 percent moisture. Each board weighs about 12.5 lb instead of the 10.4 lb dry figure, so the load is about 622 lb instead of 520. Same lumber, same store, same budget line on the payload sticker, a hundred pounds apart. That gap is the entire argument for entering a moisture content instead of trusting a single weight table.

Limits and checks before you load

The calculator assumes an average clear-wood density for the species you pick, so keep its limits in mind before you bet a towing decision on the result.

• Species averages hide range: individual boards run a few percent either side of the table value, and the southern pines split into two gravity groups, 0.51 and 0.54.
• Wet treated lumber outweighs dry tables: waterborne preservative arrives as water, so use the moisture input until the stack has dried.
• Hardware is extra: framing nails, joist hangers and hurricane ties add real pounds to a loaded bed, but they are outside the wood math.
• Grade barely moves weight: grades differ in knots and strength, not enough in density to matter for a payload estimate.
• Board feet stay nominal: the weight uses actual dimensions, the board foot count uses the name, and mixing them up inflates a weight by a third on 2x stock.

For the sizes themselves, the current American Softwood Lumber Standard, PS 20-25 is the controlling document, and the Wood handbook lists specific gravity for several hundred species beyond the dropdown here. If the job is measuring lumber rather than lifting it, the board footage calculator stays in volume units the whole way.