Comcast today announced that it will boost its data cap from 300GB per month to 1TB beginning June 1, but the company will also charge more to customers who want unlimited data.

Comcast has been trialling different caps in various cities in preparation for a potential nationwide rollout. Typically, customers would get 300GB per month and have to pay another $10 for each additional 50GB when they go over. Comcast also allowed customers to pay an extra $30 to $35 a month for unlimited data, depending on the city.

After the June 1 change, fewer customers will need to buy unlimited data—but it will cost them $50 a month to do so instead of $30 or $35. Overage fees will stay the same, $10 for each additional 50GB. Thus far, Comcast has allowed customers to exceed the cap in three "courtesy months" before charging them overage fees.

For now, the data caps are still in trial mode and are not yet applied throughout Comcast territory. "All of the data plans in our trial markets will move from a 300 gigabyte data plan to a terabyte by June 1st, regardless of the speed," Comcast's announcement today said.

The change comes as more and more customers go over the 300GB cap. In late 2013, Comcast was saying that only 2 percent of its customers used more than 300GB of data a month. By late 2015, that was up to 8 percent.

At 300GB a month, the caps were low enough that customers making heavy use of streaming services such as Netflix or Sling TV had trouble avoiding overage charges. A terabyte should provide relief for most people, as Comcast said today that "more than 99 percent of our customers do not come close to using a terabyte" and that "typical" customers use about 60GB a month.

"What can you do with a terabyte? A whole lot," Comcast said. "You can stream about 700 hours of HD video, play 12,000 hours of online games, and download 60,000 high-res photos in a month."

There's also the question of how accurate Comcast's meter is. One customer we interviewed a few months ago discovered a huge mistake in the meter, and Comcast subsequently acknowledged there was a technical error.

Comcast's caps have been imposed in various cities in Alabama, Arizona, Arkansas, Florida, Georgia, Central Kentucky, Louisiana, Maine, Mississippi, Tennessee, South Carolina, and Virginia. Officially, Comcast says its data caps aren't really "caps" because customers are allowed to go over them, though they have to pay extra when they do so.

AT&T recently decided to step up enforcement of its own home Internet data caps, which range from 150GB to 1TB a month depending on what plan a customer buys.