A Ballooning Megabyte Budget

Everyone knows how long a minute is. And your cellphone carrier keeps close tabs on how many you have used this month. Now, in the smartphone era, more people are being forced to think about how many megabytes of data they are using. But what, exactly, is a megabyte?

A megabyte is, in this context, 1,000 kilobytes — or about the size of a photo taken with a decent digital camera, or roughly one minute of a song, or a decent stack of e-mail. Therein lies the problem: Counting things like minutes and text messages is fairly easy, but there is no intuitive or natural way to gauge data use. The carriers say they are doing their best to help customers keep tabs on their data diet. But the potential for confusion — and unexpected charges — is growing as people upgrade to faster devices running on faster networks. A vast majority of smartphone owners do not come near their data limits, many studies say. But data use is predicted to climb considerably over the next few years.