Micrograms to Milligrams
Convert micrograms to milligrams instantly — one microgram is 0.001 milligrams.
| Micrograms | Milligrams |
|---|---|
| 1 µg | 0.001 mg |
| 2 µg | 0.002 mg |
| 3 µg | 0.003 mg |
| 5 µg | 0.005 mg |
| 10 µg | 0.01 mg |
| 25 µg | 0.025 mg |
| 50 µg | 0.05 mg |
| 100 µg | 0.1 mg |
How to use
- Enter a value in the Micrograms field.
- The Milligrams figure appears immediately — no button to press.
- Typing in the Milligrams field converts back to Micrograms the same way.
- Use the reference table for the values that come up most often.
Micrograms to Milligrams formula
To convert micrograms to milligrams, multiply by 0.001.
mg = µg × 0.001
Put another way, one microgram is exactly 1/1,000 of a milligram.
Why this factor: the microgram and the milligram are both defined against the kilogram, so dividing one definition by the other gives 0.001 directly. Both definitions are set out in full below.
To go the other way, divide by 0.001 — or use the Milligrams to Micrograms converter, which is the same calculation reversed.
Worked example
Take 150 µg and multiply by the factor 0.001: the result is 0.15 mg.
150 µg × 0.001 = 0.15 mg
The converter above does this for any value you type, in either direction.
What is a microgram?
A microgram is one millionth of a gram, used where quantities are vanishingly small but still matter.
Definition: Exactly 1×10⁻⁹ kilogram by SI prefix definition. Symbol µg.
Where it is used: Trace nutrients such as vitamin B12 and folate, hormone doses, and air-quality measurements.
Worth knowing: Sometimes abbreviated 'mcg' on labels specifically to avoid µg being misread as mg — a thousandfold dosing error.
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.
Micrograms vs Milligrams
The microgram and the milligram belong to the same family of units, so converting between them is usually a matter of shifting a decimal point or applying a small whole-number factor.
Frequently asked questions
How many milligrams are in a microgram?
One microgram equals 0.001 milligrams.
What is the formula to convert micrograms to milligrams?
Multiply the number of micrograms by 0.001. To reverse it, divide by 0.001 instead.
How do I convert milligrams back to micrograms?
Divide by 0.001, which is the same as multiplying by 1000.
How many milligrams are in 10 micrograms?
10 µg works out to 0.01 mg.
Is there anything to watch out for with micrograms?
Sometimes abbreviated 'mcg' on labels specifically to avoid µg being misread as mg — a thousandfold dosing error.
How is the microgram defined?
Exactly 1×10⁻⁹ kilogram by SI prefix definition. Symbol µg.