The measurement "cord" is used to refer to a quantity of wood, specifically a stack of 128 cubic feet or 4 by 8 by 4 feet. A half-cord is, self-evidently, half this amount or 64 cubic feet. It conveniently turns out to be about the amount it takes to fill an 8-foot pickup truck bed, according to the University of Nebraska-Lincoln Extension -- that is, when the wood is stacked neatly. Cords and half-cords are used to measure firewood.
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Trees to Cords
If you are cutting down your own trees for firewood and need to know how many will make a haf-cord, you must start by measuring the diameters of the trees' trunks. This is done at breast height, which is standardized at 4.5 feet off the ground. This diameter at breast height is abbreviated DBH. A tree with a DBH of 16 inches will yield a half-cord of wood. If the tree is only 10 inches DBH, it will take two to three trees for a half-cord.
There cannot be one standard weight for a half-cord of wood. For one thing, if the wood has a high moisture content, it will weigh more than if the wood were dried out. Second, different tree species produce wood with differing densities. For instance, a half-cord of dry white oak weighs more than 2,200 lbs., according to the University of Nebraska-Lincoln Extension. The same amount of spruce, meanwhile, weighs only about 1,400 lbs.
The amount of heat a half-cord can generate in the fireplace or wood stove depends on the wood's density. Dense, heavy wood can burn longer, producing more heat. Know which woods are heavy, medium or lightweight before you buy so that you can make the economical choice. For instance, if light and heavy wood are around the same in price, the half-cord of heavy wood will be the better value. Meanwhile, dried wood will always provide more heat when burned than wood high in moisture. The University of Missouri Extension says 10 to 12 percent of the wood's potential heat is lost when the wood is burned before being dried.
Wood will typically be "wet" when you get it: that is, high in moisture. Wet wood can weigh double what dry wood does, a consideration when transporting the load. Know the weight-bearing capacity of your vehicle in advance so you can choose your species of wood appropriately. Once you have the half-cord home, stack it in the sun to dry for at least a year.