Pounds to Grams

About Pounds and Grams

Pounds (lb): From the Roman libra pondo, 'a pound by weight' (the abbreviation lb comes from libra); the avoirdupois pound is exactly 0.45359237 kilograms by 1959 international agreement. Common uses: US body weight, US shipping, US livestock, US agriculture, and athletic equipment in the United States; UK food labeling sometimes still includes pounds alongside the metric kg.

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 pound and gram.

The exact relationship is grams = pounds × 453.59237, 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 pounds 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.