Think you have to wear a dedicated fitness tracker to get accurate data? Don't worry -- you may have a good excuse to skip the wristband. The University of Pennsylvania has published a study showing that smartphone apps' step counts are reasonably on the mark, at less than a 7 percent variance between their data and what observers saw first-hand. With wearables, it's all over the map. Some are very accurate, like Fitbit's One and Zip; others don't give you much of an advantage over a phone, and Nike's Fuelband was sometimes off by a wide margin.
This isn't to say that you should ditch wearables for good. The test only focused on six trackers, and didn't include either the latest devices (including smartwatches) or a wide range of activities. There are also certain situations where a phone simply isn't practical. You may not want to go on a run with your Galaxy or iPhone, for one thing. All the same, there's enough evidence here to suggest that your handset is good enough when you're only concerned about the distance you've walked in a given day.