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UnitCalculators.com

Grams to milligrams

Multiply grams by 1,000 to get milligrams.

1 g = 1,000 mgBIPM SI
g
10,000mg

10 g = 10,000 mg

How to convert grams to milligrams

The milligram is one thousandth of a gram (10⁻⁶ kg). The gram is one thousandth of a kilogram (10⁻³ kg) in the SI.

Worked example — 10 g: 10 × 1,000 = 10,000 mg.

Grams to milligrams table

Common conversions. The reverse table is on milligrams to grams.
GramsMilligrams
0.5 g500 mg
1 g1,000 mg
2 g2,000 mg
5 g5,000 mg
10 g10,000 mg
25 g25,000 mg
50 g50,000 mg
100 g100,000 mg
500 g500,000 mg

Reverse and related

About grams and milligrams

Gram (g)

1 g = 1,000 mg

Definition. One thousandth of a kilogram (10⁻³ kg) in the SI

History and origin

The gram was the original base of the metric system set out in 1795, defined as the mass of one cubic centimetre of water at the melting point of ice, before the larger kilogram was chosen as the SI base unit. It is now simply one thousandth of a kilogram.

Current use

Grams are the everyday metric unit for small masses: recipe ingredients, nutrition labels, medicine doses and postage.

Source: BIPM, The International System of Units (SI), 9th ed. (2019)

Milligram (mg)

1 mg = 0.001 g

Definition. One thousandth of a gram (10⁻⁶ kg)

History and origin

The milligram is one thousandth of a gram, part of the decimal metric system. Its small size suits doses and trace amounts.

Current use

Milligrams are the everyday unit for medication doses and for nutrients on food labels.

Source: BIPM, The International System of Units (SI), 9th ed. (2019)

Where people use this

Grams: recipe and food weights, nutrition labels, postage. Milligrams: medication doses, nutrition labels. 1 gram is exactly 1000 mg.

How we know this is right
The factor is fixed by the standards that define the units, not chosen — so it is exact, not a measurement:
1 mg = 0.001 g, so 1 g = 1 ÷ 0.001 = 1,000 mg.

Every value is carried to full double precision; the display is rounded.

Both units are defined in BIPM, The International System of Units (SI), 9th ed. (2019).

Questions people ask

How many mg in a gram?

One gram is exactly 1000 milligrams. To convert grams to milligrams, multiply by 1000.

How many mg is 5 grams?

5 grams is 5000 mg.

How many mg is 0.5 grams?

Half a gram is 500 mg.

All gram conversions