Grams to Milligrams
Convert grams to milligrams instantly. 1 g = 1000 mg. Includes the exact factor, a conversion table of common values and the definition of both units.
How to convert grams to milligrams
To convert grams to milligrams, multiply by 1000. The relationship is fixed, so the same factor works for any quantity — there is nothing to look up and nothing that changes with temperature, location or context.
mg = g × 1000
Grams to Milligrams conversion table
The values people look up most often, rounded for reading. Use the calculator above for anything in between.
| Grams | Milligrams |
|---|---|
| 1 g | 1,000 mg |
| 2 g | 2,000 mg |
| 3 g | 3,000 mg |
| 5 g | 5,000 mg |
| 10 g | 10,000 mg |
| 20 g | 20,000 mg |
| 25 g | 25,000 mg |
| 50 g | 50,000 mg |
| 100 g | 100,000 mg |
| 500 g | 500,000 mg |
| 1,000 g | 1,000,000 mg |
What is a gram?
A thousandth of a kilogram, and the practical unit for cooking by weight.
What is a milligram?
A thousandth of a gram. Standard for medication strength.
The formula
mg = g × 1000
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Grams to Milligrams
- Type the number of grams you want to convert.
- Read the result in milligrams straight away — there is no button to press.
- Check the table below for the values that come up most often, or reverse the conversion with the linked milligrams to grams page.
Grams to Milligrams — frequently asked questions
How many milligrams are in a gram?
One gram equals 1000 mg. mg = g × 1000
What is the formula to convert grams to milligrams?
The formula is mg = g × 1000. It is an exact definition rather than an approximation, so the conversion never drifts no matter how large the number.
How do I convert milligrams back to grams?
Divide instead of multiplying: one milligram is 0.001 g. The reverse converter is linked in the related tools list.
Is this conversion exact?
Yes. Both units are defined against the same base unit by international agreement, so the factor is exact — any rounding you see is only in the display, which you can widen by entering more decimal places.
Is this grams to milligrams free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
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About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed August 15, 2026 · Calculation runs client-side · No data collected · Report an error