The next time you hit the gym, take a look around. You’ll probably see a fair amount of people wearing fitness trackers. Many gym goers are turning to activity trackers to track a variety of fitness metrics, including steps taken, calories burned, heart rate and sleep.

The wearable technology industry is booming right now, with fitness trackers front and center. Millions of Americans are using fitness trackers, and their popularity is only expected to rise. Analysts predict the global sales of these wearables will grow from $2 billion in 2014 to $5.34 billion by 2019.

Despite their prominence, their accuracy has often been in question. You’ll be happy to hear that fitness trackers are more than 90% accurate at tracking steps. However, when it comes to measuring calories, they’re not as precise.

Numerous studies have been performed to determine the accuracy of fitness trackers, and they all came to the same conclusion— activity trackers do a poor job of counting calories.


One study tested 12 different devices, including the Fitbit Flex and Jawbone Up24. The researchers found: the fitness trackers underestimated calories burned by as many as 278 calories, and overestimated them by up to 204 calories. In a second experiment, the devices were off by between 69 and 590 calories.

In a similar study, researchers looked at the Fitbit Flex, One and Zip, and Jawbone Up 24 device. They found they overestimated the amount of calories burned for high intensity movements, like running, and underestimated calories for less-intense daily activities, like household chores.

This inaccuracy could be dangerous if you have a health condition and are relying on your fitness tracker for accurate data. While it may not be as risky for users without a health condition, the incorrect feedback could be hindering your health and fitness plans— either causing you to overwork yourself or keeping you from reaching your goals.

This doesn’t mean you should throw your fitness tracker in the trash. But, you should be aware they are not 100% accurate and only use them as an overall indication of your activity.

Before you commit to any fitness tracker, learn how you can try out different devices for FREE here.

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