Convert g to mg
Convert g to mg instantly. 1 g = 1,000 mg. Formula, worked examples and a quick reference table.
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One gram equals 1,000 milligrams. To convert any number of grams to milligrams, multiply by 1,000.
The converter above works in both directions and updates as you type. Below you will find the formula, a worked example and a reference table of common values.
Weight and mass conversions matter most in three places: shipping, where a rate band can turn on a single kilogram; cooking, where recipes cross between metric grams and imperial ounces; and personal weight, where Britain and Ireland use stones, the United States uses pounds, and everywhere else uses kilograms. Strictly these are mass units rather than weight units, and the distinction only bites in physics, where weight is a force measured in newtons.
g to mg formula
To go the other way, use gram = milligram ÷ 1,000.
About these units
The gram is a thousandth of a kilogram. It is the base unit of nearly every recipe outside the US, and the reason kitchen scales beat cup measures for consistency.
The milligram is a thousandth of a gram, and the standard unit for medicine doses and nutrition labels, where the quantities are far too small for grams to be readable.
Gram is also written gramme, grammes, grams, gm and gms. Milligram is also written milligramme and milligrams.
Sources
g to mg conversion table
| Gram | Milligram |
|---|---|
| 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 |
| 250 g | 250,000 mg |
| 500 g | 500,000 mg |
| 1,000 g | 1,000,000 mg |
Frequently asked questions
How many milligrams are in a gram? +
There are 1,000 milligrams in one gram.
What is 10 g in mg? +
10 g equals 10,000 mg. Multiply 10 by 1,000.
How do I convert milligram back to gram? +
Use gram = milligram ÷ 1,000. The converter above handles both directions, or see our dedicated mg to g page.
How accurate is this gram to milligram conversion? +
The factor used is 1,000, carried at full double precision. Where a unit has an exact legal definition the factor is exact rather than approximate. Rounding is applied only to the displayed result, so the answer is never a calculation done on an already-rounded number.
Is there a quick way to estimate g to mg in my head? +
Multiply by 1,000. That matches the true factor of 1,000 exactly, so no adjustment is needed for a mental estimate.