According to online sources, 1 stone = 14 lbs. So a 20-stone person weighs 280 lbs.

I stone = 14 Pounds Here is a reference to a calculator: http://www.calculateme.com/Weight/Stones/ToPounds.htm

wow, 1 stone = 14lbs? i wouldnt want anybody throwing stones like that at me.

280. 1st = 14lbs so 10st = 140lbs and 20st = 280 :-) Thank God for imperial :-)

Well 280 english lbs.But that depends on how much US pounds weigh, are they the same as UK pounds ?

1) for practical purposes: 1 stones = 14 pounds http://www.google.com/search?hl=en&q=1+stones+in+pounds&btnG=Search 20 stones = 280 pounds http://www.google.com/search?hl=en&q=20+stones+in+pounds&btnG=Search 2) "The stone is a unit of weight, that is, the force the gravitational field of the Earth exerts on a mass. The Imperial unit of mass is the slug, which weighs 32.17405 pounds -- or 2.29815 stone -- in Earth's gravitational field. The stone is part of the Imperial system of weights and measures used in the United Kingdom, and formerly used in several Commonwealth countries. It is equal to 14 pounds (more precisely avoirdupois pounds), or 6.35029318 kilograms." Source and further information: http://en.wikipedia.org/wiki/Stone_(mass%29 3) "Avoirdupois pound: The avoirdupois pound was invented by London merchants in 1303. Originally it was based on independent standards. During the reign of Henry VIII of England, the avoirdupois pound was redefined as 7,000 troy grains. Since then, the grain has often been considered as a part of the avoirdupois system. By 1758, two standard weights for the avoirdupois pound existed, and when measured in troy grains they were found to be of 7,002 grains and 6,999 grains. In the United Kingdom, the avoirdupois pound was defined as a unit of mass by the Weights and Measures Act of 1878, but having a different value (in relation to the kilogram) than it does now, of approximately 0.453592338 kg, which would make the kilogram approximately equal to 2.20462278 pounds. (This was a measured quantity, with the independently maintained artifact still serving as the official standard for this pound.) This old value is sometimes called the imperial pound, and this definition and terminology are obsolete unless referring to the slightly-different 1878 definition. In 1883 it was determined that 0.4535924277 kg was a better approximation. With the Weights and measures Act 1889 the United Kingdom legally defined the avoirdupois pound as the rounded value of 0.45359243 kg. In the United States, the (avoirdupois) pound as a unit of mass has been officially defined in terms of the kilogram since the Mendenhall Order of 1893. In 1893, the relationship was specified to be 2.20462 pounds per kilogram. In 1894, the relationship was specified to be 2.20462234 pounds per kilogram. This change followed a determination of the British pound. According to a 1959 NIST publication, the international pound differed from the United States 1894 pound by approximately one part in 10 million. The difference is so insignificant that it can be ignored for almost all practical purposes." Source and further information: http://en.wikipedia.org/wiki/Avoirdupois_pound#Avoirdupois_pound