Grams to Milligrams Converter

1 gram (g) equals 1,000 milligrams (mg).

Quick answer

To convert grams to milligrams, multiply by 1,000: 0.5 g = 500 mg.

  • 1 gram = 1,000 milligrams
  • 1 milligram = 0.001 grams
  • Formula: mg = g × 1,000
  • Quick estimate: move the decimal point three places right: 1.5 g = 1,500 mg.

1 gram = 1,000 milligrams

How to convert grams to milligrams

mg = g × 1,000

To convert grams to milligrams, multiply the number of grams by 1,000.

Example: 42 g to mg

  1. Start with the value in grams: 42 g.
  2. Multiply by 1,000: 42 × 1,000 = 42,000.
  3. Result: 42 grams = 42,000 milligrams.

Going the other way, 1 milligram = 0.001 grams, so to convert milligrams back to grams you divide by the same number. See milligrams to grams.

Where the conversion factor comes from

The kilogram is the SI base unit of mass, defined since 2019 by fixing the value of the Planck constant. Metric prefixes are exact: 1 kg = 1,000 g, 1 g = 1,000 mg, and a metric tonne is 1,000 kg.

Mental math: g to mg in your head

Move the decimal point three places to the right.

When you need to convert grams to milligrams

  • Supplement and medicine labels.
  • Chemistry and lab work.

Common mistakes

  • Mixing up mg and µg on supplement labels.

Everyday grams in milligrams

ExampleGramsMilligrams
Salt in a pinch0.36 g360 mg
A paperclip1 g1,000 mg
Teaspoon of sugar4.2 g4,200 mg

Grams to milligrams conversion table

Grams (g)Milligrams (mg)
0.1 g 100 mg
0.2 g 200 mg
0.3 g 300 mg
0.4 g 400 mg
0.5 g 500 mg
0.6 g 600 mg
0.7 g 700 mg
0.8 g 800 mg
0.9 g 900 mg
1 g 1,000 mg
1.5 g 1,500 mg
2 g 2,000 mg
2.5 g 2,500 mg
3 g 3,000 mg
3.5 g 3,500 mg
4 g 4,000 mg
4.5 g 4,500 mg
5 g 5,000 mg
6 g 6,000 mg
7 g 7,000 mg
7.5 g 7,500 mg
8 g 8,000 mg
9 g 9,000 mg
10 g 10,000 mg
11 g 11,000 mg
12 g 12,000 mg
13 g 13,000 mg
14 g 14,000 mg
15 g 15,000 mg
16 g 16,000 mg
17 g 17,000 mg
18 g 18,000 mg
19 g 19,000 mg
20 g 20,000 mg
21 g 21,000 mg
22 g 22,000 mg
23 g 23,000 mg
24 g 24,000 mg
25 g 25,000 mg
26 g 26,000 mg

More g to mg values

What is a gram?

The gram is a metric unit of mass equal to one thousandth of a kilogram.

More about grams →

What is a milligram?

The milligram is a metric unit of mass equal to one thousandth of a gram.

More about milligrams →

Convert grams to other units

Convert other units to milligrams

Frequently asked questions

How many milligrams are in a gram?

One gram is 1,000 milligrams.

How many grams are in a milligram?

One milligram is 0.001 grams.

What is the formula to convert grams to milligrams?

mg = g × 1,000.

How many mg is 1 g?

1,000 mg.