Grams to Milligrams
An instant grams-to-milligrams converter, with the formula and a reference table below.
| Grams | Milligrams |
|---|---|
| 1 g | 1000 mg |
| 2 g | 2000 mg |
| 3 g | 3000 mg |
| 5 g | 5000 mg |
| 10 g | 10000 mg |
| 25 g | 25000 mg |
| 50 g | 50000 mg |
| 100 g | 100000 mg |
How to use
- Enter a value in the Grams field.
- The Milligrams figure appears immediately — no button to press.
- Typing in the Milligrams field converts back to Grams the same way.
- Use the reference table for the values that come up most often.
Grams to Milligrams formula
To convert grams to milligrams, multiply by 1000.
mg = g × 1000
Put another way, one gram is exactly 1,000 milligrams.
Why this factor: the gram and the milligram are both defined against the kilogram, so dividing one definition by the other gives 1000 directly. Both definitions are set out in full below.
To go the other way, divide by 1000 — or use the Milligrams to Grams converter, which is the same calculation reversed.
Worked example
Take 2 g and multiply by the factor 1000: the result is 2000 mg.
2 g × 1000 = 2000 mg
The converter above does this for any value you type, in either direction.
What is a gram?
A gram is one thousandth of a kilogram, the everyday unit for food and small-object mass.
Definition: Exactly 0.001 kilogram by SI prefix definition.
Where it is used: Nutrition labels, recipes, postal rates, and laboratory weighing.
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.
Grams vs Milligrams
The gram 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 gram?
One gram equals 1000 milligrams.
What is the formula to convert grams to milligrams?
Multiply the number of grams by 1000. To reverse it, divide by 1000 instead.
How do I convert milligrams back to grams?
Divide by 1000, which is the same as multiplying by 0.001.
How many milligrams are in 10 grams?
10 g works out to 10000 mg.
How is the gram defined?
Exactly 0.001 kilogram by SI prefix definition.