Micrograms to Stone (µg to st)

1 microgram equals 1.574730444×10⁻¹⁰ stone (rounded).

1 microgram = 1.574730444×10⁻¹⁰ stone

How to convert micrograms to stone

To convert micrograms to stone, multiply the number of micrograms by 1.574730444×10⁻¹⁰. The factor is rounded to 10 significant digits. To go the other way, multiply stone by 6,350,293,180.

stone = micrograms × 1.574730444×10⁻¹⁰

Example: 10 micrograms = 1.574730444×10⁻⁹ stone.

About these units

Microgram (µg)

Metric (SI)Current unit

One millionth of a gram. Used for very small doses such as vitamin B12 and folic acid; often written mcg on labels.

Tiny doses forced the microgram into everyday use. It is one millionth of a gram, written with the SI prefix micro and the Greek letter mu, but that letter caused trouble: handwritten or badly printed, mu can look like a lowercase m, which would turn micro into milli and make a dose a thousand times too large. For that reason the US Institute for Safe Medication Practices and the FDA recommend writing mcg in medical communication, while UK prescribing guidance says microgram should be written out in full rather than abbreviated.

You meet the unit mostly on nutrition labels and in medicine, where amounts such as folic acid and vitamin B12 are given in micrograms. It also matters in laboratories. According to NIST, the old kilogram prototype gave relative uncertainties of a few parts in ten thousand at the milligram level, and fields such as pharmaceuticals and materials science increasingly need dependable accuracy down at the microgram, which was one argument for redefining the kilogram with a fundamental constant. In text where mu is unavailable, people type u or the micro sign instead.

1 microgram = 1×10⁻⁹ kilograms (exactly).

Sources: Wikipedia: Microgram; NIST: Kilogram introduction (SI redefinition)

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)

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