This is up 82 per cent compared to December 2008 when Twitter and Facebook users spent around three hours the entire month.
Facebook now has 206.9 million users, accounting for 67 percent of the global social networking pie.
The US had the largest number of social networking site users at 142.1 million unique visitors. Japan followed with 46.5 million and Brazil came third with 31.3 million unique visitors.
The average user in Australia spent the most time on social networking sites, almost seven hours per month, while users in the US, UK and Italy spent around six hours each.