Grams to Milligrams Converter
Convert grams to milligrams — multiply by a thousand. Results update as you type; exact factors shown.
One gram is 1,000 milligrams — see the exact factor, not a rounded rule of thumb.
How the grams to milligrams converter works
Mass converts through the kilogram. The avoirdupois pound has been exactly 0.45359237 kg since 1959, so an ounce is 28.349523125 g and a stone (14 lb) is 6.35029318 kg. A US short ton is 2,000 lb; an imperial long ton is 2,240 lb; a metric tonne is 1,000 kg.
Australia is fully metric under the National Measurement Act 1960; imperial units appear only in trade with the US and in older documents.
Common mass conversions
| From | To | Units |
|---|---|---|
| 0.001 g | 1 mg | grams to milligrams |
| 0.01 g | 10 mg | grams to milligrams |
| 0.1 g | 100 mg | grams to milligrams |
| 0.25 g | 250 mg | grams to milligrams |
| 0.5 g | 500 mg | grams to milligrams |
| 1 g | 1,000 mg | gram to milligrams |
| 2 g | 2,000 mg | grams to milligrams |
| 5 g | 5,000 mg | grams to milligrams |
| 10 g | 10,000 mg | grams to milligrams |
| 50 g | 50,000 mg | grams to milligrams |
| 100 g | 100,000 mg | grams to milligrams |
| 500 g | 500,000 mg | grams to milligrams |
Units in this converter and their exact factors
| Unit | Symbol | One unit in kilograms |
|---|---|---|
| milligram | mg | 0.000001 kilogram |
| gram | g | 0.001 kilogram |
| kilogram | kg | 1 kilogram |
| tonne (metric ton) | t | 1,000 kilogram |
| ounce | oz | 0.0283495231 kilogram |
| pound | lb | 0.45359237 kilogram |
| stone | st | 6.35029318 kilogram |
| US ton (short) | US ton | 907.18474 kilogram |
| imperial ton (long) | long ton | 1,016.0469088 kilogram |
FAQFrequently asked questions about mass conversion
How many milligrams in a gram?
Exactly 1,000.
What is 0.5 g in mg?
500 mg.
Why do medicines use milligrams?
Because doses are small. A paracetamol tablet is 500 mg, which is half a gram.
What is a microgram?
A thousandth of a milligram — a millionth of a gram. Vitamin doses are often quoted in them.
What is 1 mg in grams?
0.001 g.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Measurement Institute (NMI) — Australia's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.