Wearable fitness trackers have been touted as the best way to monitor your activity and health. And it feels like they’re everywhere. But a new study in JAMA indicates that the fundamental calculation done by most wearables—a record of step taken—can actually be computed just as accurately by your smartphone, if not more so.
Researchers at the University of Pennsylvania had 14 healthy adults walk on a treadmill for 500 or 1,500 steps and then do it again. During each of their walks, the participants were wearing one pedometer and two accelerometers on their waistbands, and three popular types of wearables on their wrists. They also had two smartphones, one in each pants pocket, running a total of four fitness tracking apps. The participants’ steps were also being independently counted to verify that they took the exact correct number during each trial.
The smartphones were fairly close to the correct step counts—within about 6.7 percent—whereas the wearables varied more widely. Some were extremely close, and others were off by as much as 22.7 percent.
“Since step counts are such an important part of how these devices and apps measure physical activity, including calculating distance or calories burned, their accuracy is key,” said senior researcher Mitesh Patel in a press release.
He pointed out that while fitness trackers are still relatively niche, a majority of the adult population in the United States carries smartphones. “Our findings suggest that smartphone apps could prove to be a more widely accessible and affordable way of tracking health behaviors,” he said.
Smartphones aren’t always convenient to have on you. They don’t necessarily fit in pockets, especially women’s pockets, and they aren’t as rugged as wearables are meant to be. By and large they also can’t do more specialized tracking for things like heart rate. But if shelling out a few hundred bucks for a fitness tracker doesn’t sound appealing, you might already have a decent alternative.