Cord (unit)

The cord is a unit of measure of dry volume used to measure firewood and pulpwood in the United States and Canada.

A cord is the amount of wood that, when "racked and well stowed" (arranged so pieces are aligned, parallel, touching and compact), occupies a volume of 128 cuft. This corresponds to a well-stacked woodpile 4 ft high, 8 ft wide, and 4 ft deep; or any other arrangement of linear measurements that yields the same volume.

The name cord probably comes from the use of a cord or string to measure it.

The cord-foot was a US unit of volume for stacked firewood, four feet long, four feet wide and one foot high—equal to one eighth of a cord. The symbol for the unit was cd-ft.

Definitions
In Canada, the cord is legally defined by Measurement Canada. The cord is one of three legal standards for the sale of firewood in Canada: stacked cubic metre (or stere), cubic foot, and cord.

In the United States, the cord is defined by statute in most states. The U.S. National Institute of Standards and Technology Handbook 130, section 2.4.1.2, defines a cord and provides uniform regulations for the sale of fireplace and stove wood. In the metric system, wood is usually measured in steres and cubic metres: 1 stere = 1 m3 ≈ 0.276 cords.

Maine appears unique among U.S. states by also defining a "loose thrown cord" or pile of cut firewood: "A cord of 12 or in length shall mean the amount of wood, bark and air contained in a space of 180 cuft; and a cord of wood 24 in in length shall mean the amount of wood, bark, and air contained in a space of 195 cuft. [1981, c. 219 (amd).]"

Other non-official terms for firewood volume include standing cord, kitchen cord, running cord, face cord, fencing cord, country cord, long cord, and rick, all subject to local variation. These are usually taken to mean a well-stacked pile of wood in which the logs are shorter or longer than in a legal cord, to accommodate various burners. For example, a face cord commonly consists of wood that is 16 in long. The volume of a face cord therefore is typically 1/3 of the volume of a full cord even though it is 8 ft long and 4 ft high. A face cord is also called a rick in Midwestern United States.

The term is used in other English-speaking countries, such as New Zealand, but may not have a legal definition.

The corde was a unit of volume used before metrication in several French-speaking countries (France, Belgium and Luxembourg). Its value varied from 6 - 13.5 m depending on the region, corresponding approximately 2 to 5 steres.

Heating value
One seasoned (dry) cord of Northern red oak with a heating value of 22.1 e6Btu/cord has the heating equivalent of 159 usgal of fuel oil with a heating value of 138700 BTU/usgal.

Australia
Until metrication in Australia, an imperial cord was a measurement for wood and firewood. The measurements for a cord of wood were 4 feet wide by 4 feet deep by 8 feet high, or usually a stack of wood containing 128 cubic feet (cu ft). The imperial cord enclosed 128 cu ft.