No study has been able to conclude that trackers are 100% accurate in step counting, so you may also want to take this metric with a pinch of salt, but it's usually more accurate than the calories and heart rate recorded. The steps and heart rate are just two metrics. Fitness trackers also estimate caloric burn, sleep stages, and more. All of these metrics will look slightly different on each bracelet you wear and how you wear it.
A study by Stanford Medicine concluded that six out of seven fitness trackers measured heart rate accurately. In fact, they did it within 5%. However, not one of the devices in the study calculated calories accurately. Detailed heart rate monitoring and metrics based on various heart rate data points have become increasingly popular in many fitness trackers.
How a monitor is worn, how it is placed on the wrist, and how tight the band is can affect readings. So, although fitness trackers may have gotten the number of calories burned poorly, highly accurate heart rate data is a great sign. The strap itself (fabric, with a non-slip rubber strip inside) adjusts like a dream thanks to its flat position and flush with the wrist; it also detects tension (high heart rate) automatically and offers more than 50 sports and activities to choose from. With so many factors to consider, it's hard to feel confident that you've found an accurate fitness tracker.
Fitness enthusiasts who focus on accurately tracking specific workouts, in addition to their daily activities, may find that the Garmin Vívoactive 4S is a more practical and streamlined alternative to a GPS running watch. In addition to tracking your heart rate to report exercise, some trackers use HRV and other factors, such as sleep and resting heart rate, to determine how well you recover from workouts and daily activity. In an article in The Wired Runner, the author points out that overtraining is a common cause of injury and that using a fitness tracker with heart rate monitoring can help runners become more aware of their body. Most of these fitness devices have a “sedentary warning”, which sounds when you've been sitting on your butt for too long.
Smartwatch brand Polar even claims that those with dark skin and tattoos can affect the accuracy of readings on fitness trackers worn on the wrist. We love what Suunto aims to achieve with the Suunto 3 fitness watch, a workout-oriented companion that encourages you to follow a training plan and incorporate more exercise into your life. If you want a true smartwatch with activity and workout tracking, if you are a fan of the Apple ecosystem and if you can do without a handful of features that the most advanced Apple Watch Series 7 has (our best selection of smartwatches for people with iPhones), the Apple Watch SE could deliver what you need. Accuracy varied between trackers when it came to step counting, but they tended to be better at counting steps correctly during fast walking, rather than during daily activities and intermittent walking when arm movements were more often counted as steps.