To convert grams to milligrams, multiply by 1000. So 1 g = 1000 mg and 0.5 g = 500 mg. This is exact - the SI prefix "milli" means 1/1000 by definition.
- Exact: 1 g = 1000 mg - defined by the SI prefix "milli" = 1/1000.
- 0.5 g = 500 mg. 1 g = 1000 mg. 2.5 g = 2500 mg.
- Move the decimal three places right to convert g to mg.
- To convert mg back to g, divide by 1000.
How to Use This Converter
Type any grams value in the g field and the milligrams result appears instantly. You can also type in the mg field to convert back to grams. The conversion is exact - multiply by 1000.
How Do You Convert Grams to Milligrams?
Multiply grams by 1000. The SI prefix "milli" means 1/1000, so 1 gram = 1000 milligrams by definition. Move the decimal point three places to the right.
$$\text{mg} = \text{g} \times 1000$$
Worked examples: 0.1 g = 100 mg. 0.25 g = 250 mg. 0.5 g = 500 mg. 1 g = 1000 mg. 1.5 g = 1500 mg. 2 g = 2000 mg. 5 g = 5000 mg.
Shortcut: move the decimal three places right. For 3.75 g: 3750 mg. Exact, no rounding.
How Do You Convert Milligrams to Grams?
Divide milligrams by 1000. See the dedicated milligrams to grams converter for an mg-first reference table.
$$\text{g} = \text{mg} \div 1000$$
Worked examples: 500 mg = 0.5 g. 1000 mg = 1 g. 2500 mg = 2.5 g.
Grams to Milligrams Reference Table
| Grams (g) | Milligrams (mg) | Common context |
|---|---|---|
| 0.05 g | 50 mg | Low-dose aspirin |
| 0.1 g | 100 mg | - |
| 0.2 g | 200 mg | Ibuprofen tablet |
| 0.25 g | 250 mg | Amoxicillin 250 mg |
| 0.5 g | 500 mg | Paracetamol tablet |
| 1 g | 1,000 mg | Paracetamol max single dose |
| 1.5 g | 1,500 mg | - |
| 2 g | 2,000 mg | - |
| 4 g | 4,000 mg | Paracetamol max daily dose |
| 5 g | 5,000 mg | - |
When Do You Need to Convert Grams to mg?
- Medication - pharmaceutical formulas specify drug concentrations in mg; compounding recipes work in grams.
- Nutrition labels - daily values for vitamins and minerals are in mg; total intake is tracked in grams.
- Chemistry - analytical balances read in grams; reaction calculations may require mg precision.
- Supplements - supplement containers list amounts in mg; purchasing in grams requires conversion.
Frequently Asked Questions
How many mg is 1 gram?
Exactly 1000 milligrams. 1 g × 1000 = 1000 mg. This is the SI definition - "milli" means 1/1000.
How do you convert grams to mg?
Multiply by 1000, or move the decimal three places right. For 0.75 g: move decimal → 750 mg. Exact, no rounding.
How many mg is 0.5 grams?
0.5 g = 500 mg. This is equivalent to a standard paracetamol or acetaminophen tablet.