Lumber Weight Calculator
Find how much your lumber weighs, board by board and in total, from its size, length, and quantity. It works as a wood weight calculator and a hardwood weight calculator: choose from common softwoods and hardwoods, or enter your own wood density.
- Choose US or Metric. This sets the lumber sizes you can pick and the units of the results: pounds and cubic feet for US, kilograms and cubic meters for Metric.
- For each board, pick a Size, enter the Length, and enter how many boards of that size and length you have in Quantity. For a size that is not listed, choose Custom size and enter the actual thickness and width.
- Use Add board for each other size or length, such as studs and joists in one load.
- Choose the Wood species. The density changes to match. If you know the density of your wood, enter it in Density. The reset link under the field brings back the value for the species.
- The result shows the total weight, the volume of wood, and the weight of each row. Copy the result to keep it.
The length and size fields accept whole numbers, decimals, fractions, and
mixed numbers, such as 8, 2.4,
3/4, or 1 1/2.
How lumber weight is calculated
The weight of each row is:
Weight = thickness × width × length × quantity × density
The thickness and width are the actual size of the lumber, not the nominal size it's sold by. A dry 2x4 is 1 1/2 × 3 1/2 in, and a 1x6 is 3/4 × 5 1/2 in, the minimum dressed sizes in PS 20-20, the American Softwood Lumber Standard. Using the nominal 2 × 4 in would count about half again as much wood as a 2x4 has. Check the size on your lumber, since some boards are a little larger.
With the size in inches, the length in feet, and the density in lb/ft³, that works out to:
Pounds = thickness × width × length × quantity × density ÷ 144
Wood density
The densities come from the Wood Handbook of the USDA Forest Service's Forest Products Laboratory. The handbook gives the specific gravity of each wood at 12% moisture content, and the density of the wood with its water at that moisture content is:
Density = specific gravity × 1,000 kg/m³ × (1 + 12 ÷ 100)
For example, Douglas-fir has a specific gravity of 0.48, so its density is 0.48 × 1,000 kg/m³ × 1.12 = 537.6 kg/m³ (33.56 lb/ft³).
For lumber sold as a group of species, such as Southern yellow pine, Spruce-pine-fir (SPF), Hem-fir, red oak, white oak, and hard maple, the calculator uses the average of the species in the group.
| Species | Density |
|---|---|
| Douglas-fir | 33.56 lb/ft³ (537.6 kg/m³) |
| Southern yellow pine | 38.46 lb/ft³ (616 kg/m³) |
| Spruce-pine-fir | 26.57 lb/ft³ (425.6 kg/m³) |
| Hem-fir | 27.97 lb/ft³ (448 kg/m³) |
| Western red cedar | 22.37 lb/ft³ (358.4 kg/m³) |
| Redwood | 24.47 lb/ft³ (392 kg/m³) |
| Cherry | 34.96 lb/ft³ (560 kg/m³) |
| Hard maple | 41.95 lb/ft³ (672 kg/m³) |
| Red oak | 44.75 lb/ft³ (716.8 kg/m³) |
| Walnut | 38.46 lb/ft³ (616 kg/m³) |
| White oak | 46.85 lb/ft³ (750.4 kg/m³) |
| Yellow poplar | 29.37 lb/ft³ (470.4 kg/m³) |
Wood varies within a species: the handbook gives a coefficient of variation of about 10% for the density of common domestic woods. Treat the result as an estimate. If you know the weight of one of your boards, divide it by the board's volume and enter that as the density.
Most SPF lumber sold in the US comes from Canada, but the Canadian values in the handbook have no specific gravity at 12% moisture, so the calculator uses the US-grown spruces, pines, and firs. Redwood uses young-growth wood, since most redwood lumber today comes from second- or third-growth forests. Old-growth redwood from older buildings is about 14% heavier.
Moisture content
The densities are for dry lumber at 12% moisture content. PS 20-20 calls lumber dry at up to 19% moisture, so lumber in a store or yard can be somewhat heavier than the result. Green lumber and pressure-treated lumber that hasn't been dried again hold much more water and can weigh a lot more. Lumber 5 in thick or more, such as a 6x6, is also often sold without drying.
For wet lumber, look up the density in the handbook's table of density by specific gravity and moisture content (Table 4–6), or weigh one board and divide by its volume, and enter that in Density.
Woods common outside the US, such as European whitewood and redwood, radiata pine, and Tasmanian oak, aren't listed. Enter the density from the seller or a reference for your wood. For example, the handbook gives about 480 kg/m³ (30 lb/ft³) for plantation-grown radiata pine at 12% moisture.
Examples
A stack of 2x4 studs
Ten 2x4s 8 ft long are 10 × 1.5 × 3.5 × 96 = 5,040 in³, or 2.917 ft³ of wood. In Douglas-fir at 33.56 lb/ft³, they weigh 98 lb (44 kg), about 9.8 lb each. In Spruce-pine-fir, the same studs weigh 77 lb.
A load of joists and posts
One hundred 2x6s 16 ft long and six 4x4s 8 ft long in Southern yellow pine are 95.750 ft³ of wood and weigh 3,682 lb: 1.84 US tons, or 1.67 tonnes.
Hardwood boards
Five red oak boards 1 in thick, 6 in wide, and 8 ft long, entered as a custom size, are 1.667 ft³ and weigh 75 lb (34 kg).
Metric sizes
Ten 38 × 89 mm studs 2.4 m long are 0.081 m³ of wood. In Douglas-fir at 537.6 kg/m³, they weigh 44 kg (96 lb).
FAQ
About 9.8 lb (4.4 kg) in dry Douglas-fir, 7.7 lb in Spruce-pine-fir, and 11.2 lb in Southern yellow pine. Wet or pressure-treated 2x4s weigh more.
About 31 lb (14 kg) in dry Douglas-fir and 35 lb in Southern yellow pine.
That's the actual size of a dry 2x4, and the weight depends on how much wood there is. Board feet are counted from the nominal size, but the nominal 2 × 4 in would make a 2x4 about 1.5 times as heavy as it is. To count board feet and the cost, use the Board Foot Calculator.
It depends on how much water the lumber still holds, which varies with the treatment and drying, so the calculator has no value for it. Treated lumber that hasn't been dried again after treatment is much wetter than dry lumber and can weigh a lot more. Weigh one board, divide by its volume, and enter that as the density to get the weight of the rest.
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