Stone to Pounds (st to lb)

1 stone equals 14 pounds exactly.

1 stone = 14 pounds

How to convert stone to pounds

To convert stone to pounds, multiply the number of stone by 14. This factor is exact. To go the other way, multiply pounds by 0.07142857143 (rounded).

pounds = stone × 14

Example: 10 stone = 140 pounds.

About these units

Stone (st)

Imperial (British)Current unit

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

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.

1 stone = 6.35029318 kilograms (exactly).

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

Pound (lb)

US & ImperialCurrent unit

Exactly 0.45359237 kg, divided into 16 ounces. The standard unit of weight in the US and common in the UK.

Why is pound abbreviated lb? The answer is Roman. The English word comes from the Latin libra pondo, roughly the weight measured in libra, and the symbol keeps the first word. The Roman libra was divided into 12 unciae. The avoirdupois pound of 16 ounces came into general use around 1300 and was initially equal to 6,992 troy grains; under Elizabeth I it was redefined as 7,000 grains. The UK's Weights and Measures Act 1878 set the imperial standard pound as a platinum cylinder, and the troy pound was abolished for trade the following year.

Today the pound is defined from the kilogram. The International Yard and Pound Agreement of 1959 fixed it at exactly 0.45359237 kg, and the UK's Weights and Measures Act 1963 wrote the same figure into law. Pounds remain the everyday unit for body weight, groceries and shipping in the United States and are widely used in the UK. The word also survives in odd places: a six-pounder cannon was named for the weight of its shot, not its own.

1 pound = 0.45359237 kilograms (exactly).

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

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