The average Tinder user spends 77 minutes per usage day using the app

"It’s not just all soccer and samba in Brazil at the moment. There also seems to be an increase in a passion of a third, technologically-augmented kind: an explosion in location-based dating apps, fueled by a volatile mix of delirious FIFA World Cup tourists, excited locals, and perhaps copious quantities of alcohol.
Tinder—the dating app that sees 750 million swipes and 10 million matches every day—has seen a 50% increase in downloads and usage in Brazil since the World Cup began. Brazil is Tinder’s third-largest user base behind the US and the UK, and the app is available in Portuguese.
“The average Tinder user spends more than one hour a day on Tinder, approximately 77 minutes, and that number is up by nearly 50% in Brazil since the start of the World Cup,” Tinder spokesperson Rosette Pambakian told Quartz.
Grindr, an app for gay and bisexual men, has also seen numbers spike. Compared to early June, the number of times users have opened the app has increased by 31%; and time spent on each session has jumped by 26%, a spokesperson said. Brazil is the sixth-largest market for Grindr, with 202,972 active monthly users."

Source:  Quartz, 25th June 2014

Note - I'm assuming they mean per usage day - e.g. use it for 10 days per month, spend 770 mins