The hoppus cubic foot

Cubic foot

The cubic foot is an Imperial and US customary unit of volume, used in the United States and the United Kingdom. It is defined as the volume of a cube with sides of one foot in length.-Conversions:- Symbols :...

 (or ‘hoppus cube’ or ‘h cu ft’) was the standard volume measurement used for timber

Timber

Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...

 in the British Empire

British Empire

The British Empire comprised the dominions, colonies, protectorates, mandates and other territories ruled or administered by the United Kingdom. It originated with the overseas colonies and trading posts established by England in the late 16th and early 17th centuries. At its height, it was the...

 and countries in the British sphere of influence before the introduction of metric units

Metric system

The metric system is an international decimalised system of measurement. France was first to adopt a metric system, in 1799, and a metric system is now the official system of measurement, used in almost every country in the world...

. It is still used in the hardwood trade of some countries.
This volume measurement was developed to estimate what volume of a round log would be usable timber after processing, in effect attempting to ‘square’ the log and allows for waste.
The hoppus ton (HT) was also a traditionally used unit of volume in British forestry

Forestry

Forestry is the interdisciplinary profession embracing the science, art, and craft of creating, managing, using, and conserving forests and associated resources in a sustainable manner to meet desired goals, needs, and values for human benefit. Forestry is practiced in plantations and natural stands...

. One hoppus ton is equal to 50 hoppus feet or 1.8027 cubic metres. Some shipments of tropical hardwoods, especially shipments of teak

Teak

Teak is the common name for the tropical hardwood tree species Tectona grandis and its wood products. Tectona grandis is native to south and southeast Asia, mainly India, Indonesia, Malaysia, and Burma, but is naturalized and cultivated in many countries, including those in Africa and the...

 from Myanmar

Myanmar

Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....

(Burma), are still stated in hoppus tons.

History

The English surveyor Edward Hoppus introduced the eponymous unit in his 1736 manual of practical calculations. The tables include reference to stone as well as timber, as stone can similarly suffer wastage during processing into regular pieces.

Calculation of timber volume in round logs

The following calculation can be used to estimate the usable timber in round logs

Hoppus Volume (hft) = (Mid Quarter Girth in ins.)^2 X Length (ft) / 144

One hoppus foot = 1.273 true ft3; 27.74 h ft = 1 m3; and 1 h ft = 0.03605m3. A hoppus foot is approximately 21% oversize compared with a true cubic foot.