Grams to Milligrams Converter

Grams to Milligrams

Convert grams (g) to milligrams (mg). Both measure mass and weight, and the conversion comes up in cooking, shipping, fitness work.

The Formula

`` milligrams = grams × 1000 grams = milligrams × 0.001 `

One gram is 1,000 milligrams, and one milligram is 0.001 grams.

Conversion Table

Grams	Milligrams
1 g	1,000 mg
2 g	2,000 mg
5 g	5,000 mg
10 g	10,000 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

The Other Direction

Milligrams	Grams
1 mg	0.001 g
2 mg	0.002 g
5 mg	0.005 g
10 mg	0.01 g
25 mg	0.025 g
50 mg	0.05 g
100 mg	0.1 g
500 mg	0.5 g
1,000 mg	1 g

What Each Unit Is

Grams (g) — one thousandth of a kilogram. The metric unit for small masses; cooking, nutrition and postage all work in grams.

Milligrams (mg) — one thousandth of a gram. The metric unit for doses and trace quantities.

A Sense of Scale

• A paperclip is about 1 g
• A sheet of A4 is 5 g
• A tennis ball is 58 g
• A grain of sand is about 1 mg
• An aspirin tablet is 300–500 mg
• Nutrition labels use mg for sodium

Precision

The factor 1000 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.

In Code

`javascript const gramToMilligram = (value) => value * 1000; ``

Where This Conversion Comes Up

• Cooking
• Shipping
• Fitness
• Medicine
• Manufacturing

How Many Decimals Do You Need?

Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 g with the factor truncated at each decimal place:

Decimals kept	Factor	137 g becomes	Error
0	1000	137,000	—
1	1000	137,000	—
2	1000	137,000	—
3	1000	137,000	—
4	1000	137,000	—

A rule that holds for any conversion: round once, at the end. Rounding the factor and then multiplying compounds the error through every subsequent calculation, while carrying full precision and rounding the final answer does not.

The right number of significant figures is set by your input, not by the converter. If you measured grams to three significant figures, the answer in milligrams is only good to three — writing more digits claims precision the measurement never had.

Other Conversions From Grams

The same value in every other unit this converter supports for weight:

From	To	Unit
1 g	0.001 kg	Kilograms
1 g	0.00220462 lb	Pounds
1 g	0.035274 oz	Ounces
1 g	1.5747e-4 st	Stone
1 g	1.0000e-6 t	Tons

Chaining conversions works — grams to metres to feet gives the same answer as grams to feet — but each step rounds, so a chain of three conversions carries three roundings. Convert directly where a direct factor exists.