You’ve got a limited allotment of monthly LTE data to use, so you’re careful with it. You just load up the news and read it — on a reputable website — while waiting for a coffee or the bus, let’s say. And yet at the end of the month you’ve used way more data than you feel like you should have. The culprit? Those annoying ads that get in your way anyway.

Business Insider reports this week that a new study finds ad-blockers for mobile phones aren’t just about annoyance over slow, irritating, noisy, or page-gobbling ads. Rather, they’re about preserving a precious resource: your data.

Ad content, the study found, accounted for between 18% and 79% of the data served to the user. That means on a good day, almost 1/5 of the LTE data you use up is used by ads you probably don’t even want to see. On a bad day, it might be 4/5 of your data.

Data caps and overage billing are still, despite some carriers’ efforts, a major part of the mobile landscape. Most of us have some kind of metered plan, and try to be judicious with our use of data when we’re out and about without WiFi.

So when the researchers concluded that “it is reasonable to say advertising accounts for half of all the data used” by the pages they loaded… well. That’s a lot of money out of consumers’ pockets.

That’s the logic behind the choice some European wireless carriers made back in February, when they started proactively blocking ads from being served on their mobile networks — and this study seems to back them up.

The experiment used a browser “impersonating an iPhone 6” to request mobile pages from unnamed “popular publishers.” They compared the amount of data used when ads and JavaScript were permitted or blocked, to figure out how much data each of those required to deliver.

Ads on news sites gobble up as much as 79% of users’ mobile data [Business Insider]

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