A chaldron (also chauldron or chalder) was a dry English measure of volume, mostly used for coal; the word itself is an obsolete spelling of cauldron. It was used from the 13th century until 1963 when it was abolished by the Weights and Measures Act.


The chaldron was used as the measure for coal from the 13th century, measuring by volume being much more practical than weighing low-value, high-bulk commodities like coal. It was not standardized, and there were many different regional chaldrons, the two most important being the Newcastle and London chaldrons. The Newcastle chaldron was used to measure all coal shipped from Northumberland and Durham, and the London chaldron became the standard measure for coal in the east and south of England.[1]

Many attempts have been made to calculate the weight of a Newcastle chaldron as used in medieval and early modern times. Coal industry historian John Nef has estimated that in 1421 it weighed 2,000 lb (910 kg), and that its weight was gradually increased by coal traders due to the taxes on coal (which were charged per chaldron) until 1678 when its weight was fixed by law at 5212 cwt, later increased in 1694 to 53 cwt.[1]

A London chaldron, on the other hand, was defined as "36 bushels heaped up, each bushel to contain a Winchester bushel and one quart, and to be 1912 inches in diameter". This approximated a weight in coal of around 28 cwt, or 3,136 lb (1,422 kg).[2]

The chaldron was the legal limit for horse-drawn coal wagons travelling by road as it was considered that heavier loads would cause too much damage to the roadways. Railways had standard "chauldron wagons" which were about 10 ft (3.0 m) and around 6 ft 3 in (1.91 m) high.

The value of a chaldron of coal depended on the size of the lumps of coal and also their water content. Unscrupulous merchants would purchase their coal in lumps as large as possible then sell them in smaller sizes. This was abolished by the Weights and Measures Act of 1835, which legislated that from January 1836 coal was only to be sold by weight.[3]


  1. ^ a b Ashworth, William; Mark Pegg (1986). The history of the British coal industry. Oxford University Press. pp. 559–560. ISBN 0198282826. 
  2. ^ Hutton, Charles (1815). A Philosophical and Mathematical Dictionary. p. 302. 
  3. ^ William J. Ashworth, Charles (2003). Customs and Excise. Oxford University Press. p. 289. ISBN 0199259216. 

 This article incorporates content from the 1728 Cyclopaedia, a publication in the public domain.