Choosing a broadband provider is a little like shopping blind folded: you rarely know what speed connection you'll actually get until you've handed over your first month's subscription. Also, marketing material carefully uses the phrase "up to", so consumers tend to only know about the best case scenario speeds of different providers.

To address the problem, Ookla, the company behind Speedtest.net, has just released data that shows what speed different ISPs deliver. The company's NetIndex site already ranks cities, U.S. states, and countries by their average connection speeds. The new data comes from a questionnaire that appears after someone uses speedtest.net to test their connection. In the last 30 days or so, around 100,000 people have responded.

Scroll to the bottom of this page to see the ranking of all ISPs across the U.S. At the time of writing Comcast comes out top, followed by less well known providers Charter, Optimum Online, MidContinent Communications and Road Runner. You can drill down to see the list for individual states, for example Massachusetts, and cities.

"This is the kind of data that people haven't been able to see before," says Ookla co-founder Mike Apgar, also revealing plans to have speedtest.net tell you how your connection compares to the average in your state or local area. He's also working on a "value index" that compares ISPs based on the price you pay for each Mbps you get.

"It gets a little more interesting when we get into what people are paying," says Apgar. For example, preliminary data shows that the average monthly cost of broadband in the U.S. is $47.32, at a cost of $5.06 per Mbps. Comparing states is more interesting: Washington residents pay $3.89 per Mbps, those in California $4.24 and inhabitants of Idaho $8.80. "The ultimate vision is that we'll have a site where you can compare ISPs from across the globe," Apgar adds. Given South Korea's clear lead in the global speed stakes, 26 places ahead of the U.S., it's likely the country will also dominate that list.