The numbers come from the Wood Handbook of the USDA Forest Products Laboratory, which lists the specific gravity of each species and how much water green wood holds. Weight is simply volume times density, and density depends on both the species and the water in the wood.
How to use this calculator
- Pick the species. For construction lumber sold as SPF or hem-fir, pick the spruce, fir or hemlock that is closest.
- Choose the moisture: dry indoor wood such as furniture and trim, kiln-dried construction lumber from the yard, or green wood from a tree that was just cut.
- Choose the piece. Dimensional lumber uses the real dressed size of a 2x4 or a 1x6, not its name; for a board or slab, measure it; for a log, use the average diameter of the two ends.
- Enter the length and how many pieces, or the board feet for a stack of rough hardwood.
Worked examples
A dry Douglas-fir 2x4
Wood species: Douglas-fir (coast) · Piece: Dimensional lumber · Nominal size: 2x4 · Length: 8 ft
- Weight
- 9.8 lb
- Density
- 33.6 lb per cu ft
- Wood volume
- 0.29 cu ft
- Board feet
- 5.33 board ft
A bundle of southern pine 2x6 boards
Wood species: Southern yellow pine (loblolly) · Piece: Dimensional lumber · Nominal size: 2x6 · Length: 12 ft · Pieces: 20
- Weight
- 490 lb
- Per piece
- 24.52 lb
- Density
- 35.7 lb per cu ft
- Wood volume
- 13.75 cu ft
- Board feet
- 240.00 board ft
A green red oak log
Wood species: Red oak (northern) · Moisture: Green (freshly cut) · Piece: Log · Diameter: 16 in · Length: 8 ft
- Weight
- 681 lb
- If all heartwood
- 703 lb
- If all sapwood
- 660 lb
- Density
- 61.0 lb per cu ft
- Wood volume
- 11.17 cu ft
A black walnut slab
Wood species: Black walnut · Piece: Board or slab · Thickness: 2 in · Width: 24 in · Length: 6 ft
- Weight
- 77 lb
- Density
- 38.5 lb per cu ft
- Wood volume
- 2.00 cu ft
A stack of white oak
Wood species: White oak · Piece: Board feet · Board feet: 100
- Weight
- 396 lb
- Density
- 47.5 lb per cu ft
- Wood volume
- 8.33 cu ft
How wood weight is worked out
The Wood Handbook gives each species a specific gravity: how heavy the wood itself is compared with water, which weighs 62.43 lb per cubic foot. The water held in the wood adds its share on top, as a percentage of the dry wood's weight. Multiply the two and you have the density; multiply the density by the volume and you have the weight.
For dry wood, the calculator uses the handbook's figures at 12 percent moisture content, about where seasoned wood settles indoors. For green wood, it uses the specific gravity of the fresh wood and the water that fresh heartwood and sapwood hold.
How much common woods weigh, dry
- Western red cedar: about 22 lb per cubic foot, one of the lightest.
- Eastern white pine: about 24 lb per cubic foot.
- Douglas-fir: about 34 lb per cubic foot.
- Southern yellow pine (loblolly): about 36 lb per cubic foot.
- Black walnut: about 38 lb per cubic foot.
- Red oak: about 44 lb per cubic foot, and hard maple the same.
- White oak: about 48 lb per cubic foot.
- Hickory: about 50 lb per cubic foot, the heaviest wood in the list.
Green wood is much heavier
A freshly cut tree is full of water. Red oak heartwood holds about 80 percent of its dry weight in water, and the sapwood of western red cedar about 249 percent, more than twice the weight of the wood itself. Sapwood, the light outer part of the trunk, often holds far more water than heartwood, so for green wood the calculator shows both and takes the middle.
Wood loses that water as it dries, quickly at first, so a log or a stack of firewood gets much lighter over a season or two.
How dry is dry
- Lumber sold as dry, S-DRY or KD may hold up to 19 percent moisture; framing lumber is kiln-dried to about 15 percent on average.
- Hardwood for furniture, floors and cabinets is dried further, to 6 to 8 percent, and wood indoors settles near 12 percent.
- Air-dried wood stays wetter: 15 to 20 percent for softwoods and 20 to 25 percent for dense hardwoods.
- Green lumber holds 35 to 200 percent of its dry weight in water, or even more, and firewood burns well only below 20 percent.
Lumber is smaller than its name
A 2x4 is dressed to 1.5 by 3.5 inches, and a 1x6 to 0.75 by 5.5 inches. The calculator weighs the real size, while the board feet it shows use the nominal size, the way lumber is sold. For rough hardwood sold by the board foot, enter the board feet: they are close to the real volume of rough boards.
Common questions
How much does a 2x4 weigh?
It depends on the wood and how dry it is. Pick the species, keep Dimensional lumber and 2x4, and enter the length: the first example above weighs a dry Douglas-fir 2x4 of the usual length. A wet, freshly treated or green board weighs a good deal more.
Which wood is the heaviest?
Of the woods here, hickory is the heaviest when dry, at about 50 lb per cubic foot, followed by black locust and white oak. Western red cedar is the lightest, at about 22 lb per cubic foot.
How do I find the weight of a log?
Choose Log and Green, then enter the average of the diameters at both ends and the length. The calculator treats the log as a cylinder, so bark and taper make the real log a little different.
Does wet wood weigh more than dry wood?
Yes, often much more. The water in fresh wood can weigh as much as the wood itself, or more in the sapwood of some softwoods. Dry wood still holds some water, which is why the dry figures are at 12 percent moisture content.
What is the specific gravity of wood?
It is how heavy the wood substance is compared with the same volume of water. The Wood Handbook bases it on the weight of oven-dry wood, so it can be compared between species; the moisture in the wood is then added on top.