How to estimate the weight of wood
The weight of a board or beam equals its volume times the density of the species. Density varies from about 370 kg/m³ for cedar to over 800 kg/m³ for hickory, so species matters as much as size.
The formula
Weight = length × width × thickness × quantity × density
Use the actual dimensions, not the nominal ones. A nominal 2×4 is planed to 1.5 × 3.5 inches; a 2×6 to 1.5 × 5.5 inches; a 1×6 to 0.75 × 5.5 inches.
Worked example
Ten 2×4s, 8 ft long, in Douglas fir (about 530 kg/m³ when dry):
- Volume of one board: 96 × 3.5 × 1.5 = 504 cubic inches.
- Total volume: 5,040 cubic inches ≈ 2.92 cubic feet (0.083 m³).
- Weight: 0.083 × 530 ≈ 43.8 kg ≈ 96.5 lb, or about 9.7 lb per board.
- Board feet: 35.
Typical densities at 12% moisture
| Species | kg/m³ | lb/ft³ |
|---|---|---|
| Western red cedar | 370 | 23 |
| Eastern white pine | 400 | 25 |
| Spruce-pine-fir | 450 | 28 |
| Douglas fir | 530 | 33 |
| Southern yellow pine | 600 | 37 |
| Black walnut | 610 | 38 |
| Red oak | 700 | 44 |
| Hard maple | 705 | 44 |
| White oak | 755 | 47 |
| Hickory | 820 | 51 |
These are averages: individual boards vary by 10% or more.
Moisture changes everything
Kiln-dried lumber is sold at about 12 to 19% moisture content. Green lumber, straight from the sawmill, can contain as much water as wood fiber, and pressure-treated lumber is often still wet from treatment. Both can weigh 50 to 100% more than dry wood. Use the moisture adjustment to account for it: 50% is a reasonable guess for pressure-treated lumber bought fresh.
Why it matters
- Transport: check your vehicle’s payload before loading a pickup with lumber.
- Structures: the dead load of a deck, pergola or loft includes the weight of the wood itself.
- Shipping: freight is priced by weight, and hardwoods add up quickly.
- Handling: a 16 ft oak beam can be too heavy for one person to lift safely.