What is stone?
A stone is a unit of mass used primarily in the United Kingdom and Ireland, equal to 14 pounds. It is mainly used to express human body weight in everyday conversation.
Real-world uses
The stone is used primarily in the UK and Ireland for expressing body weight (e.g., "I weigh 11 stone"). It appears on bathroom scales sold in Britain and is the preferred unit in British medical consultations for patient weight discussions.
History
The stone has been used in the British Isles since at least the 14th century for weighing agricultural goods. Its value varied historically (from 4 to 32 pounds depending on the commodity) before being fixed at 14 pounds by the Weights and Measures Act of 1835.
Common mistakes
Assuming a stone is used outside the British Isles—it is virtually unknown in the US, continental Europe, or most other countries. Also, forgetting that 1 stone = 14 pounds, not 10 or 12.
What is milligram?
A milligram is a metric unit of mass equal to one thousandth of a gram. It is commonly used in pharmaceutical dosing, nutritional content labelling, and laboratory chemistry.
Real-world uses
Milligrams are the standard unit for pharmaceutical dosages (e.g., 500 mg ibuprofen), nutritional supplement quantities, and blood test results such as cholesterol levels (mg/dL). Environmental scientists measure pollutant concentrations in mg/L.
History
The milligram was established with the metric system's prefix conventions in the 1790s. Its importance grew dramatically with modern pharmacology, where precise small-mass measurements became critical for drug safety and efficacy.
Common mistakes
Confusing milligrams with micrograms—a factor-of-1000 error that can be dangerous in medication dosing. The abbreviation "mcg" is sometimes used for micrograms to avoid confusion with "mg."
When is this conversion used?
Converting between stone and milligram is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region.
Worked examples
1 stone = 6,350,293.18 milligram
1 milligram = 0.000001 kilogram
How to convert stone to milligram
To convert stone to milligram, multiply the value by 6,350,293.18.
To convert milligram back to stone, multiply by 1.574730e-07.
Measurement standards
The kilogram is defined by fixing the Planck constant to exactly 6.62607015 × 10⁻³⁴ joule-seconds, as established at the 26th General Conference on Weights and Measures in 2018. This ended the last SI definition based on a physical artefact.
Did you know?
The International Prototype of the Kilogram, a platinum-iridium cylinder stored near Paris since 1889, was found to have drifted by about 50 micrograms relative to its copies over a century — roughly the mass of a fingerprint.
Quick reference: stone to milligram
| stone | milligram |
|---|---|
| 0.1 | 635,029.318 |
| 0.5 | 3,175,146.59 |
| 1 | 6,350,293.18 |
| 2 | 12,700,586.36 |
| 5 | 31,751,465.90000001 |
| 10 | 63,502,931.80000001 |
| 25 | 158,757,329.5 |
| 50 | 317,514,659 |
| 100 | 635,029,318 |
| 250 | 1.587573e+09 |
| 500 | 3.175147e+09 |
| 1,000 | 6.350293e+09 |
Common values
| stone | milligram | |
|---|---|---|
| A paperclip | 0.15747304 stone | 1,000,000 milligram |
| A smartphone | 27.55778277 stone | 175,000,000 milligram |
| A bag of sugar | 0.15747304 stone | 1,000,000 milligram |
| Average adult human | 11.02311311 stone | 70,000,000 milligram |
| A small car | 188.9676533 stone | 1.200000e+09 milligram |