Little wonder, then, that millions of people wear some kind of fitness tracking device every day and that the worldwide market is worth billions.

“The short answer is: It depends,” Assistant Professor of Kinesiology and Epidemiology at the University of Wisconsin-Madison, Lisa Cadmus-Bertram told Digital Trends.

They generally also provide some estimate of your energy expenditure or calories burned, and they may estimate your sleep quality.

“With two main caveats – people who move very slowly or have unusual gaits typically find that their steps are undercounted, sometimes by quite a lot and that’s true even with research grade pedometers.”

For most people the counts are pretty good but check your step count on two different fitness trackers or compare it to your smartphone’s estimate and you’ll see differences.

“A smartphone worn in a pants pocket should be able to calculate steps very accurately.”

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