The Most Accurate Devices for Counting Steps

Women walking
Ariel Skelley/Blend Images/Getty Images.

The market is flooded with activity trackers and apps for counting your daily steps. You can wear a tracker on your waist or wrist, or use an app built into your smartphone. Yet it is unclear which method is the most accurate. A research study conducted in August 2014 at the University of Pennsylvania sought to answer this question.

Fourteen healthy adults walked on a treadmill at 3 mph (20 minutes per mile) for 500 and 1500 steps while using 10 devices simultaneously:

  • Three devices on their waistband: a pedometer (Digi-Walker SW-200 by Yamax) and two accelerometers (Zip and Fitbit One)
  • Three devices on the wrist (Fitbit Flex, Jawbone UP24, and Nike Fuelband)
  • iPhone 5s in one pants pocket with three apps running simultaneously: Fitbit, Withings Health Mate, and ProtoGeo Oy Moves 
  • Samsung Galaxy S4 in the other pants pocket running the ProtoGeo Oy Moves app

The step counts generated by the devices were compared against a gold standard, which was a manual count by one of the researchers using a tally counter. (You may have seen event staff use these devices to count the number of people entering an arena or stadium.) The 14 participants completed the 500 step and 1500 step walking sessions twice, for a total of 56 sessions.

The waist-worn pedometer and accelerometers were the most accurate, with step counts within a tight range of 0.3% lower to 1.0% higher than the manual step counts.

The Fitbit One and Fitbit Two accelerometers worn on the waistband were the most accurate of all devices and apps. These devices, when worn in the correct position, detect the motion in the hip that occurs with each step. So it makes sense that they were the most accurate for counting steps. 

The smartphone apps were slightly less accurate, with a range of error of -6.7% to +6.2%.

But considering that you don't need a separate device, you might find that the slight decrease in accuracy may be acceptable. Keep in mind that the study participants had the smartphones in their pants pocket. Results may be different if the phone is kept in a purse or bag. 

The wrist-worn devices were the least accurate, underestimating steps by-22.7% to -1.5%. But the discrepancy for the group was largely driven by the Nike Fuelband, which yielded less than 400 steps during the 500 step walking session. 

Be cautioned that participants in this small study were generally young women with normal body weight. Results might not be the same in different individuals, such as overweight older men. The participants were also walking at a moderate pace.

In conclusion, the waist-worn pedometer and accelerometers were the most accurate for counting steps, the smartphone apps were close behind, and the wrist-worn trackers were the least accurate. Other factors such as convenience, appearance, and other features may also be important to consider when deciding which approach to use.

If you're interested monitoring more than steps, learn more about how to track duration, distance, speed, and heart rate while walking or running. Also learn about how to track sedentary behavior or INactivity -- another important predictor of health.

[Mention of a commercial product or service does not constitute an endorsement.] 


Case MA, Burwick HA, Volpp KG et al. Accuracy of Smartphone Applications and Wearable Devices for Tracking Physical Activity Data. JAMA 2015;313(6):625-626. 

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