An equivalent of 138 pounds is approximately 62.6 kilograms. One kilogram is equal to 2.2 pounds. Determining how many kilograms equals 138 pounds requires dividing 138 pounds by 2.2 pounds per kilogram.
The kilogram is a standard unit of mass within the International System of Units, also known as the metric system. This system is based on tens, so conversions within the system require only moving a decimal point. The pound is a standard unit of mass within the U.S. System of Customary Units, a system used primarily within the United States. Conversions within this system and between the two systems require more involved computation.