The study said the number was up 14.2 percent from a year ago and growth will push that number up to 2.33 billion by 2017.
The highest penetration of social network users, according to eMarketer, is in the Netherlands, at 63.5 percent. Norway was second at 63.3 percent, followed by Sweden (56.4 percent), South Korea (54.4 percent), Denmark (53.3 percent), the United States (51.7 percent) and Finland (51.3 percent).
A majority of residents were also on social networks in Canada (51.2 percent) and Britain (50.2 percent, according to the report based on data from research firms, government agencies, media outlets and company reports.
The 1.61 billion figure represented 22 percent of the world's estimated population, the survey said.
The report said India is seeing the highest growth this year of 37.4 percent, though only 7.7 percent of the population uses social networks. Indonesia's numbers will climb 28.7 percent and Mexico will grow by 21.1 percent, eMarketer said.
All three of those countries are also high-growth areas for Facebook, the world's largest social network with more than one billion users.
The US remains the country with the greatest number of Facebook users, at 146.8 million, but with India's large population and expected growth rate, it will have the largest Facebook population of any country by 2016, according to the report.
