Project Fi has always been a great solution for those who use less than about 4GB of data per month, but now Google's giving the nod to people who want more. A new feature called "Bill Protection" effectively gives Project Fi users an unlimited data option, taking on the big carrier competition that has swung back to heavily promoting unlimited data plans.

So here's how it works. From the start, everything is the same as it always has been. You pay $10 per month for each gigabyte of data you use, and any data you don't use you aren't charged for. But with Bill Protection, once you hit 6GB of data, or $80 for the month ($20 "Fi Basics" + $60 of data), your bill is capped — but you continue to get data service, just like a flat-rate unlimited plan from other carriers.

Really, it's the best of both worlds. In months when you use less than 6GB of data, you only pay for the data you used — and your bill is going to be lower than it would be with an unlimited plan from any other carrier. If you have a heavy month of usage and you crest over 6GB, it's all included and billed as a flat $80. Not only does that $80 figure line up nicely with the competition, but it also is effectively much lower since most unlimited plan users don't actually use over 6GB of data per month every single month. For group plans, the throttle threshold varies as you add more people.

Bill Protection also applies to your international data usage as well, where data used outside of the U.S. is still billed identically to data used at home.

The only catch, as is always the case with "unlimited" plans, is that Project Fi does start to throttle speeds once you've hit 15GB of data usage for the month. At that point, your speeds drop to 256kbps. Somewhat counteracting that is the ability to switch back to full speed if you want to start paying again, at the usual rate of $10 per gigabyte. Other carriers start to throttle in the 15-25GB range (save for T-Mobile, which is even higher), and often don't offer any sort of full-speed buyout option, so it seems like a fine compromise to me. That 15GB of data usage on Fi used to cost you $170 for the month, too — and now it's just $80.

Now you don't have to be scared to use 'too much' data on Project Fi.

For anyone who regularly uses lots of data, say 10GB per month, Project Fi is now merely competitive with the big four U.S. carriers — and even a tad more expensive, depending on what promotions and how many lines you have. But I say that Bill Protection is "highly competitive" because no matter what you may think, a majority of people don't actually use that much data. They may use 6GB+ a couple months out of the year, but the rest of the time they're using less but still paying the same amount for an unlimited plan. In these cases, Project Fi is cheaper than the competition, and now with Bill Protection those people also won't be scared of using data when they need to.

Bill Protection is rolling out starting today for both individual and group plans — just keep an eye on your Project Fi account.