Offering free WiFi can get a café more customers, and they're browsers not table-hogs, according to a study of Paris coffee shops.

The study tracked WiFi usage at five Paris branches of coffee chain Columbus Café over three months.

According to the chain's WiFi provider Free-Hotspot.com, the sites attracted three to five times more users per day than paid-for rivals, but those users stayed online for less time on average than paying users.

Free-Hotspot.com's VP Joe Brunoli claimed that the study confounded the popular idea that free WiFi would lead to Internet junkies hogging tables during busy times such as the lunch hour.

"Instead, usage tends to be in the afternoon, which is traditionally a down-time for the hospitality industry," he said. Only three percent of usage was after the cafés' 8pm closing time, he added.

Connection stats showed the cafe hotspots attracted nine to ten users a day Monday to Friday, falling to six a day at weekends. That sounds tiny, but Brunoli claimed that usage at pay-hotspots can be as low as one or two connections a day.

The average length of connection was 89 minutes, which Brunoli said was shorter than expected but made sense in hindsight.

"It's free, so there's no fear that you're wasting money," he explained. "Connection-hogging is more of a problem for paid schemes, where people think 'I've paid for this, so I'm going to use it!'"

He added that if each user spends an average of 3 Euro, the extra business generated will easily cover the 25 Euro a month cost of providing the DSL connection. Hotspot installation costs around £90, he said, while ongoing maintenance is paid for by his company from its advertising revenue.

That assumes that WiFi users are indeed additional customers, which isn't necessarily true of course. However, Columbus Café's marketing director Luc Heitz said that WiFi is important for keeping existing customers as well.

"WiFi access is one more amenity, one more added service that we can offer to make our existing customers feel at home, and to attract new customers," he said. "Most of the customers using the service are business people or students, who are our main target.

"It is difficult to say if the free WiFi service is encouraging them to come into the café or not, but what we can say is that these people have been regularly using the service since it was installed. I'm sure they've been talking about the service with friends and family, and thanks to that, more and more people are now coming to the café."