Convert kilograms to stones

Body weight in Britain is given in two units at once: whole stones and the pounds left over. The notation 11 st 4 lb means eleven stones and four pounds, which is 71.67 kilograms.

You turn the decimal result from the converter into that notation in two steps. The figure before the point is the whole stones. Multiply what comes after the point by 14 and you get the pounds. For 11.02 stone that gives 11 stones and 0.3 of a pound, so in conversation you hear “eleven stone”.

Speech shortens it further: “eleven four” means 11 st 4 lb. The highest the pounds ever go is thirteen, because fourteen makes another stone.

The notation table below gives ready values across the whole body-weight range. The opposite direction, from the notation to kilograms, is handled by the stone to kilograms converter.

The stone is in everyday use in the United Kingdom and Ireland, and almost exclusively for body weight.[1] Goods there are weighed in kilograms and labels give grams, so the unit kept one specific area and holds on to it firmly. British bathroom scales still have a stone mode alongside kilograms.

The legal standing of the stone is split in two. The Weights and Measures Act of 1985, implementing the European directive, removed the stone from the list of units permitted in trade, so goods there are sold in kilograms.[1] Human body weight sat outside that rule, and there the stone survived in full.

The United States works differently. Americans give body weight in pounds alone: where a British speaker says “11 stone 4”, an American says “158 pounds”. Both figures describe the same weight in the imperial system, in two different units.

Australia, Canada and New Zealand moved to kilograms at metrication, so you will rarely hear the stone there. The unit held on in two countries, and in both it went deep into the language.

This works as a simple test of where a figure came from: a notation with two units points to Britain or Ireland, a lone pound figure to the United States. American values convert in the pounds to kilograms converter.

The name says outright what the unit began as: a stone. In medieval trade the counterweight was often a real stone of agreed mass, kept at the town weighing house, and goods were compared against it.

Every trade picked a stone of its own. Glass was weighed in stones of 5 pounds, wax, sugar and pepper in stones of 8, lead in stones of 12. A survey from 1880 listed stones running from 4 all the way to 26 pounds across British towns.[1] A merchant therefore had to know the goods as well as the number.

The tidying up began with Edward III in 1350, who set the wool stone at 14 pounds, a figure Henry VII confirmed in 1495. A single measure covering all goods arrived only with the Weights and Measures Act of 1835, and today’s fourteen pounds comes from it.

That is where the number comes from, the one that looks arbitrary from a metric point of view. Fourteen pounds is an inheritance from the wool trade.