Unit converter
Milligrams to Grams Converter
Use this tool to change milligrams into grams. Both belong to the metric system, so the step is a clean factor of a thousand: one gram contains 1,000 milligrams, which means one milligram is 0.001 grams. The conversion shows up on medicine labels and supplement bottles, on nutrition panels that list vitamins and minerals in milligrams, and in the lab or kitchen when a recipe or method specifies a tiny mass. Type the milligram figure and the gram value appears instantly, with a reference table for common amounts.
1 milligram = 0.001 grams
Common milligrams to grams values
| Milligrams | Grams |
|---|---|
| 1 mg | 0.001 g |
| 2 mg | 0.002 g |
| 5 mg | 0.005 g |
| 10 mg | 0.01 g |
| 20 mg | 0.02 g |
| 50 mg | 0.05 g |
| 100 mg | 0.1 g |
How to convert
- Begin with the mass in milligrams.
- Divide by 1,000 to obtain grams, because a thousand milligrams make one gram.
- In practice this just moves the decimal point three places to the left.
- To convert grams back to milligrams, multiply by 1,000 instead.
- A quick check: 500 mg is half a gram, and 100 mg is a tenth of a gram.
grams = milligrams / 1000
The metric prefix "milli" denotes one thousandth, so a milligram is a thousandth of a gram. Dividing a milligram figure by 1,000 yields grams; multiplying grams by 1,000 returns milligrams. The factor is exact and built into the SI definitions.
- mg
- the mass in milligrams you start with
- 1000
- milligrams in one gram, by SI definition
Worked example
A 250 mg paracetamol portion is 250 divided by 1,000, which equals 0.25 g. A 75 mg iron tablet works out at 0.075 g once you shift the decimal point three places.
Key facts
- One gram is exactly 1,000 milligrams; one milligram is 0.001 g.
- A standard 500 mg tablet is half a gram.
- The "milli" prefix always means one thousandth across SI units.
- A grain of table salt weighs roughly 0.06 mg, far below a single gram.
Tips
- Count the zeros: dropping three places turns 1,500 mg straight into 1.5 g.
- When a recipe mixes units, convert everything to grams first so the totals add up cleanly.
Frequently asked questions
How many grams in 1 mg?+
One milligram is 0.001 grams, a thousandth of a gram.
How many milligrams are in a gram?+
Exactly 1,000. The prefix "milli" means one thousandth, so 1,000 of them rebuild a single gram.
Why are drug doses written in milligrams?+
Active ingredients are often present in tiny amounts, and milligrams give a readable whole number rather than a long string of zeros after a decimal point.
Is a microgram the same as a milligram?+
No. A microgram is a thousand times smaller; 1,000 micrograms make one milligram, and a million make one gram.
Things to watch
- Mixing up milligrams and grams on a dose is a thousandfold error; double-check the unit on any medicine label.
- Do not confuse milligrams with millilitres; one measures mass, the other volume, and they only match for water by coincidence.
Sources
Last updated: 2026-01-01
Conversions use internationally defined factors. Provided for general use; verify critical measurements independently.