Grams to Kilograms Converter

Grams to Kilograms

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

The Formula

`` kilograms = grams × 0.001 grams = kilograms × 1000 `

One gram is 0.001 kilograms, and one kilogram is 1,000 grams.

Conversion Table

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

The Other Direction

Kilograms	Grams
1 kg	1,000 g
2 kg	2,000 g
5 kg	5,000 g
10 kg	10,000 g
25 kg	25,000 g
50 kg	50,000 g
100 kg	100,000 g
500 kg	500,000 g
1,000 kg	1,000,000 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.

Kilograms (kg) — defined since 2019 by fixing the Planck constant — the SI base unit of mass. Originally the mass of a litre of water, then a platinum-iridium cylinder near Paris until 2019.

A Sense of Scale

• A paperclip is about 1 g
• A sheet of A4 is 5 g
• A tennis ball is 58 g
• A litre of water is 1 kg
• A laptop is 1.5–2 kg
• Checked baggage allowance is often 23 kg

Precision

The factor 0.001 is exact by international agreement, not a rounded approximation. Any imprecision in a result comes from your input, not the conversion.

In Code

`javascript const gramToKilogram = (value) => value * 0.001; ``

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	0	0	100.0000%
1	0	0	100.0000%
2	0	0	100.0000%
3	0.001	0.137	—
4	0.001	0.137	—

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 kilograms is only good to three — writing more digits claims precision the measurement never had.