Your heart is racing, and sweat is running freely down your face. You’ve just finished a fantastic and grueling workout. You flip your wrist to access the touchscreen on your Fitbit tracker, pressing it to end the workout.
Eagerly checking the Fitbit App on your iPhone or other smartphones, you see how many calories that workout just burned and see that it was 700. Not too bad of a calorie burn.
But how reliable is that number? How accurate is Fitbit at tracking your heart rate, calories, and steps you took?
Whether it’s a Fitbit Charge 3, or Ionic, or any of their wearable tech, can you rely on the information is tracks? We’ll take a look at what studies have shown about the accuracy of Fitbit devices.
Fitbit trackers and smartwatches collect personal data in several different categories. You can track your daily steps, calories, heart rate, and sleep.
You’ll get much information to review daily on your Fitbit app, and the idea is that you can make adjustments based on that data, as well as get motivated in reaching your health and fitness goals.
Fitbit devices do have some accuracy issues but do give you a general sense of how you have performed. If you have serious health issues that need monitoring, you should consult a medical professional who uses a specialized medical device. But, if you’re generally trying to get healthy and want a picture of how you’re doing, the Fitbit is accurate enough.
We’ve all heard the number 10,000 when it comes to how many steps we should be taking every day. That number wasn’t just a marketing ploy to get you to buy fitness trackers, and there are actual medical benefits to hitting that mark.
To help you track your daily progress, Fitbit uses your sex and height — you enter these details on the Fitbit app — to determine your stride length. All devices use a 3-axis accelerometer to count your steps. The sensor also determines the duration, frequency, intensity, and patterns of your movements.
But, are the steps Fitbit count reliable?
This question was studied, and Fitbit steps tracking is accurate about half the time, with higher accuracy when jogging with the Fitbit on the wrist, or while on the ankle during slow walking.
Folks looking to lose weight, or maintain current weight, often track their daily caloric intake. Diet is the key to a healthy weight, especially when compared to how many calories you burn during the day, whether you’re active or sedentary.
Fitbit devices use an algorithm to try and help you with the calories burned part of the weight-loss equation.
When you set up your Fitbit app, you enter information about yourself, such as sex, height, weight, and age. The app uses this data to calculate your base metabolic rate and compares it to your daily activity, and heart rate, to determine an estimation of calories burned.
Getting a full and restful night’s sleep plays a vital role in our overall health. Quality sleep touches and improves mental health, physical health as well as the quality of life.
Fitbit trackers monitor sleep patterns and the quality of sleep you get at night. Using motion detectors and their PurePulse heart rate monitors, Fitbit claims it can track time spent in light sleep, deep sleep, and REM sleep stages.
Fitbit determines you’re asleep by lack of movement and your heart rate. On the surface, this makes perfect sense as your heart rate should lower while asleep, and you shouldn’t be moving.
Studies show that the sleep data Fitbit compiles is not very accurate, and certainly not as accurate as a sleep study in a professional lab would provide you.
You get a general sense of the amount of time spent in bed but take the stage details with a grain of salt.
Fitbit uses your heart rate to help formalize your calories burned and sleep quality. It also tracks and provides information detailing what your resting heart rate is. Having a lower resting rate indicates a healthier lifestyle and fitness trackers like Fitbit can help work to lower your resting heart rate.
Using an optical heart-rate sensor that comes with every device, green LEDs are flashed into your wrist to determine the amount of blood flowing through your capillaries. The changes in volume indicate your pulse and heart rate.
Studies have shown that Fitbit monitors heart rate close to accurate when at rest, but as you engage in vigorous activities, it tends to underestimate your heart rate. Fitbit isn’t alone as most wearables had similar inaccuracies, and none compare to more accurate chest strap monitors.
Fitbit Accuracy for Floors Climbed
Fitbit devices employ an altimeter sensor to detect when you and your tracker experience a change in elevation. It counts every 10 feet gained as a floor climbed.
However, if you check it after a sweaty workout on the Stairmaster or elliptical, sorry, it won’t count elevation on stationary machines as there is no change in the barometric pressure, which Fitbit uses to help determine elevation.
Floors climbed is calculated accurately from Fitbit. However, using barometric pressure to determine elevation gains can be problematic based on weather conditions. What Fitbit devices can not determine is if the change in pressure is due to your climbing or a change in the weather.
Which Fitbit device is the most accurate?
Fitbit has a wide variety of activity trackers that they offer consumers. Are any of them more accurate than others?
Is theFitbit Alta less accurate than the Ionic, just because it’s cheaper than other devices? What about other Fitbit trackers?
Most of the devices use the same technology and sensors when it comes to step counting, calories burned, and other health data. Generally, Fitbits are going to perform in the same way, and the difference in devices is other smartphone features that you get with models such as the Versa or the Ionic.
The Apple Watch achieved an error rate of 2.5% when monitoring heart rate during a walking test. That was the best in the test and better than the Fitbit Surge’s error rate, which fell between 6.5 and 8%.
Fitbit Versus Samsung Fitness Watch Accuracy
In the same study, Samsung Gear S2 had the highest error rate among both rigorous activities and overall heart monitoring.
Fitbit Versus Garmin Accuracy
Garmin wasn’t included in the Stanford study; however, other studies suggestthat Garmin is among the best of all the fitness trackers in measuring your VO2max. This is an indicator that determines the amount of oxygen used during intense physical activity and can be an indicator of cardiovascular fitness.
Fitbit devices came loaded with default systems and follow those when tracking calories, steps, and other data. To optimize your device, be sure to sync with the Fitbit app and enter your personal information.
Steps and calories are tracked based on information such as your height, weight, age, so be sure to keep it up to date. There are some other things you can do to get the most out of your tracker.
Set your stride length
If you don’t set a stride length, Fitbit determines it by height and sex. While that generally captures your stride, it’s not the most accurate. To get a more accurate accounting of your steps, try setting your stride length.
The first thing you need to do is find a track or some other area where you are sure of the length and then walk it, counting your steps — at least 20 steps. Divide the distance by the number of steps, and you have your stride length.
Now enter the Advanced Settings on your App and enter your stride length.
Wear the tracker on your non-dominant wrist
Most folks use their dominant hand for activities such as eating and writing. If you wear your Fitbit tracker on that arm, it may count some of those activities as extra steps, since swinging arms are part of the step tracking formula.
Wearing it on your non-dominant hand lessens the chance that extra steps are counted. Make sure that you’ve indicated on the app which wrist you are wearing the device.
Improve sleep tracking
If you aren’t sure about the sleep data your device is tracking, you can try to change the sensitivity of the sleep tracker from the app. In the Advanced Settings, you can toggle sleep tracking from ‘Normal’ to ‘’Sensitive”.
Fitbit trackers are more accurate in some areas than they are in others. However, they do give you an accounting and data of your fitness that can still be useful in your fitness journey.
If you want to get a consistent, general, sense of how many calories you’ve burned, steps taken, and resting heart rate, you will find Fitbit trackers useful. The need for more accurate tracking for medical reasons should be done with the assistance of a medical professional who will have access to more accurate devices used for such purposes.
Overall, Fitbits are accurate enough and are valuable tools in not only tracking, but providing motivation in improving general fitness.
Andy is a long-time writer covering sports, tech, and the local arts scene in Seattle, Washington. He is an avid hockey fan, weight lifter, and fitness tracker fanatic. His work has appeared on ESPN Seattle, Sportsnet in Canada and most recently NHL.com.