While there are many weight scales in the world, most countries use one of two major systems to measure weight. The first system is the imperial system which uses pounds and ounces to measure weight. The other system is known as the metric system and it is used primarily in science-related contexts.
The metric system is based on grams, kilograms, and kilos. There are 1000 grams in a kilogram, 1000 kilograms in a metric ton. One kilogram equals 2.2046 pounds which is rounded up to 2.2 pounds for simplicity's sake.