Consider two neighboring island countries called Euphoria and Bellissima. They each have 4 million labor hours available per month that they can use to produce rye, jeans, or a combination of both. The following table shows the amount of rye or jeans that can be produced using 1 hour of labor. Rye Jeans
Country (Bushels per hour of labor) (Pairs per hour of labor)
Euphoria 4 16
Bellissima 6 12

Initially, suppose Bellissima uses 1 million hours of labor per month to produce jeans and 3 million hours per month to produce rye, while Euphoria uses 3 million hours of labor per month to produce jeans and 1 million hours per month to produce rye. Consequently, Euphoria produces 15 million pairs of jeans and 20 million bushels of rye, and Bellissima produces 8 million pairs of jeans and 48 million bushels of rye. Assume there are no other countries willing to trade goods, so, in the absence of trade between these two countries, each country consumes the amount of jeans and rye it produces.

Bellissima's opportunity cost of producing 1 pair of jeans is of rye, and Euphoria's opportunity cost of producing 1 pair of jeans is of rye. Therefore, has a comparative advantage in the production of jeans, and has a comparative advantage in the production of rye.

Suppose that each country completely specializes in the production of the good in which is has a comparative advantage, producing only that good. In this case, the country that produces jeans will produce million pairs per month, and the country that produces rye will produce -- million bushels per month.