How it works
The calculator multiplies the volume of wood by its density at the moisture content you enter.
Volume = Actual thickness × Actual width × Length × Pieces
Below 30 % moisture: G = Gb ÷ (1 − 0.265 × Gb × (1 − MC ÷ 30))
At 30 % or more: G = Gb
Density = 1000 kg/m³ × G × (1 + MC ÷ 100)
Weight = Volume × Density
Gb is the basic specific gravity (ovendry weight, green volume) from Table 5–3a of the USDA Wood Handbook, MC the moisture content in percent. These are the handbook’s Equations 4–13 and 4–14.
Where the densities come from
The USDA Forest Products Laboratory’s Wood Handbook (FPL-GTR-282, 2021) lists the specific gravity of clear wood for each species, green and at 12 % moisture. Dry wood shrinks, so the same dry weight sits in a smaller volume; the handbook’s Equation 4–13 adjusts the green specific gravity for that, and Equation 4–14 adds the weight of the water. For coast Douglas-fir (Gb 0.45) at 12 % moisture that gives about 543 kg/m³ (33.9 lb/cu ft).
Nominal and actual sizes
US lumber is named by its nominal size; the board you buy is smaller after drying and planing. The presets use the dry dressed sizes in the American Wood Council’s NDS Supplement Table 1B. For metric lumber or anything else, choose custom and enter the size you measure.
Weight of a load
For a delivery or a roof rack, add up the stacks you carry: enter the number of pieces of each size and add the totals. Treated lumber, wet lumber and green timbers are heavier than the dry figure.
Worked example
Inputs
- Board size
- 2x4 (1-1/2 × 3-1/2 in)
- Length
- 8 ft
- Number of pieces
- 1
- Wood species
- Douglas-fir (coast)
- Moisture content
- 12 %
Result
- Wood volume
- 0.292 cu ft
- Density used
- 33.9 lb/cu ft
- Weight per piece
- 9.88 lb
- Total weight
- 9.88 lb (0.0049 short tons)
Common mistakes
- Using nominal sizes as real sizes. A 2x4 is 1-1/2 × 3-1/2 in, so its volume is about 34 % smaller than 2 × 4 in suggests.
- Using the dry weight for green lumber. Above about 30 % moisture the wood stops shrinking but keeps getting heavier – northern red oak at 80 % moisture weighs nearly half as much again as at 12 %.
- Assuming all softwood weighs the same. Southern pine is noticeably denser than spruce or cedar.
- Ignoring pressure treatment. Treated lumber is often delivered wet with treatment solution and weighs more until it dries.
Assumptions and limits
- Volume uses the actual dressed size times the length times the number of pieces.
- Density follows the Wood Handbook’s Method 1, from the basic specific gravity in Table 5–3a and the moisture content, assuming a fiber saturation point of 30 %.
- The species figures are averages for clear wood. Knots, resin, treatment chemicals and moisture differences within a board are not modeled.
- A custom density is used as entered; the moisture field does not change it.
Frequently asked questions
How much does a 2x4 weigh?
An 8 ft 2x4 is 1-1/2 × 3-1/2 × 96 in, or 0.292 cu ft. Coast Douglas-fir at 12 % moisture weighs about 33.9 lb per cu ft by the Wood Handbook’s figures, so the board weighs about 9.9 lb. The same board in white spruce is lighter, and green it is heavier.
How do you calculate the weight of wood?
Multiply the volume by the density. The Wood Handbook works out the density from the species’ specific gravity and the moisture content – for wood below 30 % moisture it also allows for the shrinkage that makes dry wood denser.
How much does green lumber weigh compared with dry?
Much more. Northern red oak is about 688 kg/m³ (43 lb/cu ft) at 12 % moisture by the handbook’s equations, and 1,008 kg/m³ (63 lb/cu ft) green at 80 % moisture.
Why is the weight different from a pounds-per-foot table?
Tables of weight per foot, such as AWC’s NDS Supplement Table 1B, list weights for a few fixed densities. This calculator uses the density of the species and moisture you choose.
Sources
- Wood Handbook – Wood as an Engineering Material (FPL-GTR-282), Chapters 4 and 5 — USDA Forest Service, Forest Products Laboratory. Basic specific gravity (green rows of Table 5–3a), e.g. coast Douglas-fir 0.45, loblolly pine 0.47, northern red oak 0.56; Eq. 4–13 Gx = Gb ÷ (1 − 0.265 Gb (1 − x ÷ 30)) below fiber saturation (30 %) and Eq. 4–14 ρx = ρw Gx (1 + x ÷ 100), ρw = 1,000 kg/m³.
- NDS Supplement (2018), Table 1B – Section Properties of Standard Dressed (S4S) Sawn Lumber — American Wood Council. Standard dressed sizes: 1x4 3/4 × 3-1/2 in to 1x12 3/4 × 11-1/4 in; 2x4 1-1/2 × 3-1/2 in to 2x12 1-1/2 × 11-1/4 in; 4x4 3-1/2 × 3-1/2 in; 4x6 3-1/2 × 5-1/2 in; 6x6 5-1/2 × 5-1/2 in.
- NIST Handbook 44, Appendix C – General Tables of Units of Measurement — National Institute of Standards and Technology. Exact unit definitions: 1 in = 2.54 cm, 1 yd³ = 27 ft³, 1 US gal = 231 in³, 1 lb = 0.45359237 kg.
Method reviewed November 5, 2026