The equivalent of 123 pounds is 55.79 in kilograms. The formula used to convert from pounds to kilograms divides the total number of pounds by 2.2 pounds per kilogram. For 123 pounds, the formula is 123 pounds divided by 2.2 pounds per kilogram equals 55.79 kilograms.
In the conversion formula, the pound unit cancels out to leave only the kilogram unit.
The kilogram is a unit of weight in the metric system of measurement that is used throughout most of the world. The imperial system of measurement used primarily in the United States and Canada measures weight in pounds, ounces and tons.