On the basis variation found in the distribution of sex ratio, the world is divided into four categories:

1. The countries with surplus female population. 

2. The countries which have female population more than males. 

3. The countries which have more number of males than that of females. 

4. The countries with surplus male population.

1. The countries with surplus female population: In this group, those countries are included where more than 1050 sex ratio is found. In which western European, countries, United States of America, Canada, Southern part of South America, female population is in large surplus in comparison to the males.

2. Countries with more female population than males: In this category, those countries are included where sex ratio from 1000 to 1050 is found. Poland, Mongolia, Belarus, Kazakhstan, Ukraine,Thailand, Cambodia, Myanmar and Southern African countries are included in this group of countries.

3. Countries which have more male population than females: In this group, countries where sex ratio is in between 950-1000. The countries like Australia, New Zealand, China, Korea, Mexico, Brazil, Iran and Cuba are included in this category. Males are here more than females.

4. Countries with surplus male population: The sex ratio in the countries of this group is less than even 950. India represents the countires of such group. The falling sex ratio is a matter of serious concern here.