However the overall figure disguised a stark difference between men and women, with female respondents preferring a good gossip to a good time between the sheets.
According to the YouGov survey conducted over the Internet, 37 percent of Britons rank having sex at the top of their list of activities that don't cost a penny.
That was more than the next three highest options combined gossiping with friends (18 percent), window shopping (nine percent) and going to a museum (six percent).
"During the credit crunch our famed British upper lip might not be as stiff as before but other parts still are," said Lisa Power, head of policy at the Terrence Higgins Trust, the sexual health charity that commissioned the poll.
However, while 53 percent of men ranked sex as number one, only 21 percent of women put sex atop their list, with 28 percent saying they preferred gossiping with friends.
It also showed that passion levels may be tied to the cold weather, with 43 percent of Scots rating sex as their favourite freetime activity, compared to 35 percent of Londoners.
By contrast, a study by the Institute for Social and Economic Research at the University of Essex concluded that declining house prices in Britain increase the risk of divorce.
The study, published in September, found that "negative house price shocks significantly increase the risk of partnership dissolution."
The YouGov survey interviewed 2,144 people over the Internet between November 21 and 23.