Milligrams to Grams
Enter milligrams and read grams. One gram is 1,000 mg, so divide by 1,000: a 500 mg tablet holds 0.5 g of the active ingredient.
Formula: g = mg × 0.001
- Milligram (mg)
- One thousandth of a gram and one millionth of a kilogram. It is the usual unit for drug doses, vitamins, minerals and sodium on nutrition labels.
Mg to grams table
| Milligrams (mg) | Grams (g) |
|---|---|
| 1 | 0.001 |
| 2 | 0.002 |
| 3 | 0.003 |
| 4 | 0.004 |
| 5 | 0.005 |
| 6 | 0.006 |
| 7 | 0.007 |
| 8 | 0.008 |
| 9 | 0.009 |
| 10 | 0.01 |
| Milligrams (mg) | Grams (g) |
|---|---|
| 12 | 0.012 |
| 15 | 0.015 |
| 20 | 0.02 |
| 25 | 0.025 |
| 30 | 0.03 |
| 40 | 0.04 |
| 50 | 0.05 |
| 60 | 0.06 |
| 75 | 0.075 |
| 100 | 0.1 |
Milligrams on labels and prescriptions
Tablet strengths, supplement facts and the sodium line on a food label are all given in milligrams. Converting to grams helps when you add up a day's total or compare a label in grams with one in milligrams. Two slices of bread at 230 mg of sodium each, plus a soup at 890 mg, come to 1,350 mg, or 1.35 g.
Medicine is the one place to be slow and exact. Read the strength on the package, convert only if the instructions are in a different unit, and confirm the result with a pharmacist when a dose depends on it.
Supplement labels add another trap: some list amounts in micrograms (mcg) next to milligrams. 400 mcg of folate is 0.4 mg, which is 0.0004 g. Convert each line to the same unit before comparing two products.
Watch the leading zero
Write 0.5 g, never .5 g. A missed decimal point is a known cause of dosing errors, and a leading zero makes the point hard to miss.
- 0.5 g = 500 mg
- 0.05 g = 50 mg
- 0.005 g = 5 mg
Small prefixes in the metric system
The SI builds every unit with the same prefixes: kilo for a thousand, milli for a thousandth, micro for a millionth. That is why the step from milligrams to grams is the same as from grams to kilograms and from milliliters to liters, a factor of 1,000. The full list sits in the SI Brochure.
The next step up is grams to kg, and kitchen amounts in US units are on grams to oz.
Mg to grams questions
How many milligrams are in a gram?
1,000. Milli means one thousandth, so a milligram is a thousandth of a gram.
What is 250 mg in grams?
0.25 g.
Why do some labels write 1,000 mg instead of 1 g?
The two are exactly equal. Labels sometimes use 1,000 mg instead of 1 g so that it lines up with other ingredients listed in milligrams.
How is mg different from mcg?
A microgram (mcg or µg) is a thousandth of a milligram. 1 mg = 1,000 mcg, so confusing the two on a label means a thousandfold error.