Cellphone carriers are nothing if not cunning. The more expensive data options buys more data than you could ever use, while the less expensive options are bare-bones enough to scare you into paying more, even if you don’t know how much data you actually use. The solution is simple: find out.

You can check your data consumption on your service provider’s Web site. If you don’t want the bother of constantly logging in, and a possible lag in updating your data logs, there are apps available to do this job for you. For instance. Android users on any carrier can enter their account information into a free app called 3G Watchdog, which can be set to send data use as total transfers approach monthly limits. You may be surprised at how much you use: in the USA, Android users average 582 MB a month; iPhoners rack up 492.

Although we’ve grown used to effectively unlimited home broadband connections, the proliferation of 3G and 4G wireless access in laptops means we need to get back into the habit of minding our bits when we’re not connected to Wi-Fi. Wireless providers typically include a free, basic data-tracking app with their wireless adapters. For Windows users who want more detailed tracking – or don’t really trust their wireless providers – a free app called NetWorx conveniently displays data consumption in numerical or graph form, and can even archive detailed reports in Word and Excel formats. (Alternatively, BitMeter OS sends your consumption information to a local website, which, when you are on your home network, you can visit from any computer in your house.) Mac users can try a similar app called SurplusMeter, which tracks data usage against monthly allowances.