Kilograms to Grams

About Kilograms and Grams

Kilograms (kg): The SI base unit of mass; defined since 2019 by the Planck constant, replacing a physical platinum-iridium artifact (Le Grand K) that had served as the definition for 130 years. Common uses: Body weight (everywhere except the US), shipping and freight, food packaging, athletics (Olympic lifts, international powerlifting), and any large-scale industrial measurement.

Grams (g): Originally defined in 1795 as the mass of one cubic centimeter of water at 4°C; now defined as one thousandth of a kilogram, with the kilogram defined since 2019 by the Planck constant. Common uses: Cooking (especially baking), nutrition labels, postal weight for small parcels, jewelry, and almost any precise mass measurement outside the United States.

How the conversion works

Mass conversions use the SI definition: 1 pound is exactly 0.45359237 kilograms. The factor above is the exact ratio between kilogram and gram.

The exact relationship is grams = kilograms × 1000, which the calculator at the top of this page applies in both directions. Type into either field and the other updates immediately.

When this conversion matters

Converting between kilograms and grams comes up wherever weight & mass measurements move between systems — from one country's conventions to another's, from a scientific reference to a practical specification, or from one industry's working unit to another's. The calculator and reference table above cover the everyday range; for unusual values you can type any number into either field.