Stone is a unit of weight but how much is a stone? Well, it is equal to 14 pounds (6.35029318 kg). Different values for this unit were in use in different regions at different times, but nowadays the value of 6.35029318 kilograms is accepted all over the world.

“Stone” was first mentioned by Richard de Wyche, headmaster of Bishop’s College, Kirkby Lonsdale, in 1330. The origin of the name is unclear. As early as 1585 stone weights were banned for sale in England by the Act of Parliament.

Stone is sometimes abbreviated to st., especially in written records when clarity or pronunciation may suffer otherwise (e.g., “12lb 8st” instead of “twelve pounds eight stone”). For many purposes, this can be shortened further to “st”.

Although the word “stone” has been used historically to denote a weight-based upon the avoirdupois system of units, other systems include different values such as: In some contexts, no particular weight is specified and the term “stone” becomes vaguer, referring only to “a [particular] weight for [some purpose]” without specifying the actual size or weight.

Many countries have redefined their stone in terms of a metric unit. Since July 1959 the United States and other English-speaking countries have typically used the metric in conjunction with stone: either as a simple conversion (10 pounds = 6.35029318 kilograms) or in conjunction with another system of units (20 hundredweight = 12 stones).

The British imperial system of measurement has been replaced by an internationally agreed system which is based on the kilogram, but like many old measurements, many people still use older forms such as “stone” to describe masses less than 50 kg. The following conversions apply to the pound; each is correct in context, but the exact value of a “stone” varies from country to country and can vary within one:

The metric system uses weights expressed in grams and kilograms. Conversion between them involves the calculation of mass. 1 stone = 14 pounds = 6.35029318 kilograms is approximately equal to:

1 gram ≈ 15.432 grains

1 pound ≈ 0.45359237 kilograms

10 pounds ≈ 4.54609 kilograms (rounded)

Often, for convenience, people will say they weigh X stones plus Y pounds rather than giving their weight in both measurements; this does not give an answer mathematically accurate but gives one that is easy enough for most people to deal with.

The stone is used in the British Isles, the Channel Islands, and Ireland. It was originally a unit of mass (force) equal to 14 pounds (6.35029318 kg), but since 1969 it has been defined as 6.35029318 kg, which makes it the same as the metric unit kilogram. The Imperial Standard Yard was defined in 1855. This contained length equal to 0.914 metre; this definition replaced an older one based on the “Thousand Yard” standard, established in 1666 by King Charles II under an Act of Parliament termed “An act for erecting Standards for the Weights and Measures”.

Before metrication in Britain, various systems were used there; these included various usages in different areas. The “stone” in some of its usages was closer to 14 pounds (6.35029318 kg), but it could also be 11 pounds (5.000293175 kg) or 13 pounds (5.859293416 kg).

The stone is traditionally used within the farming and haulage industries, although metric units are becoming more common. It remains an important unit of weight in the building industry, although it is no longer a mandatory unit for tradesmen dealing with bricklaying other than laying blocks or flagstones or other heavy masonry units where imperial measures are still preferred by traditional builders. Many measurements using the stone as a unit are rounded to the nearest 5 lbs; this avoids misplaced precision when working with quantities that have been rounded to the nearest 1 lb.

In the British weights and measures system, the stone is no longer used for trade; it does remain in use within some sectors of industry and commerce. For example, public houses use a barrel, two imperial gallons (1.201208 imp gal; 4.5459 liters) or four imperial pints (2.0408 imp pt; 946.35294 milliliters). This is known as a firkin and is equal to one-quarter of a quarter-hundredweight (cwt); to denote trading terms such as “one stone” would be misleading in many contexts since the numerical value may not relate to anything in either pound weight or stone weight.

One stone equals 14 pounds (6.35 kilograms) I’m pretty sure it still is in use but you are correct that the calculations to 8 decimal places have no practical use anymore. If you ever want to convert to kg, there are calculators that will do that for you on your phone or laptop just type into google “kg stones” or something similar choice is up to you depending on what device/app you have at the time.

It has been suggested that one should say ‘I weighed X stones plus Y pounds’. This would avoid being ‘off’ by 1 grain if someone says they weigh 179 lb saying they actually weigh 178.7 lb using imperial measurements or 176.56779759375 weighings 179.5 kg using metric measurements.

In the United States, customary units of mass are more commonly used than in Britain, and sometimes confusion arises because their values differ from those of British units. In particular, the US stone is 16 pounds (7.2612796 kg) whereas a British stone is 14 pounds (6.35029318 kg). The corresponding imperial/metric values are 6.35029318 kg vs 6.17500038 kg respectively; both of these stones measure roughly 0.984022 lb/lbf or 32 oz/sq ft..

In addition to the stone being different from that used in Britain, it must be emphasized that any abbreviations for pound such as “lb” and “lbs” can be confused with the short form for ounce, which is “oz”. In some cases, the abbreviation “Lb” was used to denote a pound of mass. This notation seems to have been used for paper or cardboard shipping crates and has survived until at least 2015 on some packages.

In Canada and the United Kingdom, the stone is not currently in widespread use as a unit weight; however, it remains in use in agriculture and allied trades such as those farms specializing in livestock production where there are specific requirements with respect to the permitted maximum weight for transportation or sale such as dairy produce, lambs or calves. The stone is also often used by gardeners and landscapers as a unit of mass approximating 16 kg, and it is still in everyday use by bakers for measuring ingredients such as sugar.