As smartphones have gotten more powerful, users have gotten hungrier for more and more high-speed cellular data. In just the past 18 months, average data consumption has more than doubled, according to the NPD Group, a market research firm. But how do you know how much data you really need? Buy too much and you’re wasting money. Buy too little and you could owe overage fees or your data speeds could be “throttled,” or slowed to the point of uselessness. Here’s what to ask to pick the right data package for today’s world:
“How much data am I using now?”
The best way to gauge your needs is to check your phone bills, which should tell you how much data you use each month. The average smartphone owner nowadays uses 2.9GB, reports NPD Group. But light users don’t need much: Thirty percent of smartphone owners currently use 500MB.
“How much are my kids using?”
Between streaming Netflix, checking Facebook, and posting to Instagram, young people run through data more quickly. While the average customer 55 or older needs just 1.4GB a month, the average young adult uses more than double that. If your kids are on your family plan, you may need to budget for more gigabytes.
“Can I conserve more data?”
Now that free public Wi-Fi networks have become more common, you don’t always need cellular data to access the Internet on your phone. Instead, the average smartphone user consumes a whopping 11.3GB of Wi-Fi data every month, up from just 5GB a year and a half ago. If you can connect to Wi-Fi much of the time, switch to Virgin Mobile’s Wi-Fi Lovers Delight plan or a “Wi-Fi first” plan, or just buy a traditional plan with a smaller data package.
“Am I using my phone as a television?”
That’s a surefire way to run through your data allotment. Fifty to sixty percent of all data consumption arises from video and social media, estimates the NPD Group’s Brad Akyuz. Streaming media services such as Netflix and Hulu Plus are big data drains, he says. But if you’re mostly watching YouTube, 5GB will probably suffice.
“Do I really need unlimited data?"
Unlimited data plans are back again at Sprint, T-Mobile, and MetroPCS—but unless you’re a Netflix junkie (see the prior answer), you probably don’t need one. Unlimited plans are like restaurant buffets, says Jon Colgan of CellBreaker, a startup that helps people get out of their cellphone contracts: “Most people don’t eat as much as they think they’re going to eat.” Plus, carriers have pledged to notify customers before imposing overage charges, so data fees shouldn’t take you by surprise. Before you buy an unlimited plan, make sure you can’t find a cheaper plan already offering more data than you need.
“Is this data plan really unlimited?”
Read advertisements for cellphone service plans carefully. Some carriers promising “unlimited data” will actually limit your high-speed, 4G LTE data to a couple of gigabytes per month. Once you use up that allotment, you’ll have unlimited access to slower data—but you’ll have trouble loading pages quickly and streaming video. Usually, carriers will explain when plans have a high-speed data limit, but the FTC just imposed a $100 million fine on AT&T for allegedly slowing data speeds on grandfathered unlimited plans without telling customers. Make sure you'll get what you pay for.
Read next: The Best Cellphone Plans of 2015
This story has been adapted from "Find Your Perfect Cell Plan," originally published in MONEY magazine's July 2015 issue.