Milligrams to Stones
An instant milligrams-to-stones converter, with the formula and a reference table below.
| Milligrams | Stones |
|---|---|
| 1 mg | 1.57473e-07 st |
| 2 mg | 3.14946e-07 st |
| 3 mg | 4.72419e-07 st |
| 5 mg | 7.87365e-07 st |
| 10 mg | 1.57473e-06 st |
| 25 mg | 3.93683e-06 st |
| 50 mg | 7.87365e-06 st |
| 100 mg | 1.57473e-05 st |
How to use
- Enter a value in the Milligrams field.
- The Stones figure appears immediately — no button to press.
- Typing in the Stones field converts back to Milligrams the same way.
- Use the reference table for the values that come up most often.
Milligrams to Stones formula
To convert milligrams to stones, multiply by 1.57473044e-07.
st = mg × 1.57473044e-07
Why this factor: the milligram and the stone are both defined against the kilogram, so dividing one definition by the other gives 1.57473044e-07 directly. Both definitions are set out in full below.
To go the other way, divide by 1.57473044e-07 — or use the Stones to Milligrams converter, which is the same calculation reversed.
Worked example
Start with 150 mg. Multiply by 1.57473044e-07 to get 2.3621e-05 st.
150 mg × 1.57473044e-07 = 2.3621e-05 st
The converter above does this for any value you type, in either direction.
What is a milligram?
A milligram is one thousandth of a gram — the standard unit for drug doses and micronutrients.
Definition: Exactly 1×10⁻⁶ kilogram by SI prefix definition.
Where it is used: Medication dosages, vitamin and mineral content, and analytical chemistry.
What is a stone?
A stone is fourteen pounds, still the customary unit for body weight in Britain and Ireland.
Definition: Fourteen avoirdupois pounds, so exactly 6.35029318 kilograms.
Where it is used: Personal body weight in the UK and Ireland, where weight is usually given as stones and pounds.
Worth knowing: Effectively unused in the United States, where body weight is quoted in pounds alone.
Milligrams vs Stones
The milligram is a metric unit while the stone is an imperial unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many stones are in a milligram?
One milligram equals 1.57473044e-07 stones.
What is the formula to convert milligrams to stones?
Multiply the number of milligrams by 1.57473044e-07. To reverse it, divide by 1.57473044e-07 instead.
How do I convert stones back to milligrams?
Divide by 1.57473044e-07, which is the same as multiplying by 6350293.18.
How many stones are in 10 milligrams?
10 mg works out to 1.57473e-06 st.
Is there anything to watch out for with stones?
Effectively unused in the United States, where body weight is quoted in pounds alone.
How is the milligram defined?
Exactly 1×10⁻⁶ kilogram by SI prefix definition.