Stone (st)

Imperial (British)Current unit

14 pounds (6.35 kg). Still the everyday unit for body weight in the UK and Ireland.

1 stone = 6.35029318 kilograms (exactly).

1 stone = 6.35029318 kilograms

About the stone

As the name says, the first stones were literal stones. People used them as weights, and surviving examples include Roman-era pieces made in multiples of the Roman pound and a 16th-century bronze one-stone weight bearing the English royal arms. The size was not fixed: a statute of about 1300 gave 5 pounds for glass, 8 for sugar and spices and 12 for lead, while in 1772 the Encyclopaedia Britannica noted that a stone of beef was 8 pounds in London, 12 in Hertfordshire and 16 in Scotland. Edward III set 14 pounds for wool and other goods in 1350.

The Weights and Measures Act 1835 clarified the legal trade units, with 14 pounds to the stone and 28 to the quarter. Trade use ended with metrication, in Ireland in 1983 and in the UK with the Weights and Measures Act 1985, yet the stone refuses to die. In Britain and Ireland people still say they weigh 11 stone 4, meaning 11 stone plus 4 pounds, or about 71.7 kg. It is also used in sports such as boxing, wrestling and horse racing. A single stone, at 6.35 kg, is a convenient chunk of body weight to talk about.

Sources: Wikipedia: Stone (unit); NIST Guide to the SI, Appendix B.8 (mass conversions)

Stone conversion chart

1 stone expressed in every other weight & mass unit:

Unit1 stone
Kilograms6.35029318
Grams6,350.29318
Metric Tons0.00635029318
Pounds14
Ounces224
Milligrams6,350,293.18
Micrograms6,350,293,180
Carats31,751.4659
Short Tons0.007
Long Tons0.00625
Troy Ounces204.1666667
Daltons3.824235936×10²⁷
Earth Masses1.063308861×10⁻²⁴
Solar Masses3.193557449×10⁻³⁰
Quintals0.0635029318
Grains98,000
Drams3,584
Hundredweight (US)0.14
Hundredweight (UK)0.125
Quarters (UK)0.5
Slugs0.4351333024
Troy Pounds17.01388889
Pennyweights4,083.333333
Scruples4,900
Apothecaries' Drams1,633.333333
Roman Pounds19.30767157
Roman Ounces231.7625248
Attic Talents0.2424146122
Attic Minas14.54487673
Attic Drachmas1,454.487673
Obols8,726.926038
Shekels (biblical)552.199407
Hebrew Talents0.220496291
Monme1,693.411515
Kin10.58382197
Kan1.693411515
Qian (Chinese)1,270.058636
Liang (Chinese)127.0058636
Jin (Chinese)12.70058636
Dan (Chinese)0.1270058636
Catties (Hong Kong)10.5
Taels (Hong Kong)168
Tola544.4444444
Seers6.805555556
Maunds0.1701388889
Zolotniks1,488.650965
Funts15.50678089
Poods0.3876695222
Libras (Castilian)13.80219473
Arrobas (Spanish)0.5520877892
Arrobas (Brazilian)0.4233528787

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