Is Fitbit Calories Burned Accurate?


One of the most popular products in the fitness industry right now is the Fitbit. The Fitbit allows you to track footsteps, heart rate, calories, and a number of other features related to your health. How accurate is this device, though? 

More specifically, is Fitbit calories burned accurate? According to several studies, Fitbit is more accurate than other fitness trackers for monitoring calories burned. However, many Fitbit trackers are incredibly inaccurate, some as much as 50%. Still, Fitbits serve a good function for keeping you motivated. 

With that in mind, let’s talk more about how accurate the Fitbit is for tracking burned calories. In this article, we cover their accuracy ratings, factors that go into estimated burned calories, and more. Let’s get started. 

Is Fitbit Calories Burned Accurate? 

When it comes to fitness trackers, Fitbit is considered one of the most reliable, efficient, and accurate brands. Nevertheless, all fitness trackers, including Fitbit, tend to overestimate how many calories are burned per day. Other times, Fitbits can underestimate the number of calories burned.   

One of the most popular Fitbit models is the Fitbit Charge 2. In a study conducted by researchers at Aberystwyth University, the researchers wanted to know exactly how accurate the Fitbit Charge 2 was. 

In their studies, they found that the tracker was incredibly accurate when measuring calories burned while running. The Fitbit underestimated the calorie burn by just 4%, which is impressive. 

In contrast, the Fitbit Charge 2 is way less accurate when it comes to measuring the number of calories burned while walking. Most models overestimated the number of calories burned by more than 50%. This is incredibly far off from the real results. 

In the same study, the researchers wanted to compare the accuracy of the Fitbit Charge 2 to cheaper Fitbit trackers on the market. Interestingly, the results were reversed. The cheaper products underestimated the number of calories burned from running by up to 40%. At the same time, some of the cheaper options overestimated calories burned from walking by 2%. 

What does this study tell us about Fitbit accuracy? Simply put, it tells us that the Fitbit tends to be more accurate when tracking the number of calories burned from running. 

If you are just walking throughout the day and want to know how many calories you burned, however, the Fitbit is less accurate, and you could find a cheaper alternative that more closely estimates the number of calories burned. 

Are Some Models More Accurate Than Others? 

In the study above, the only Fitbit model that was looked at was the Fitbit Charge 2. Other studies have found that different Fitbit models tend to be more accurate than others. In fact, the most accurate Fitbit is the Fitbit Surge. Studies have shown that it has an error rate of slightly over 25%, making it one of the most accurate in the industry. 

A 25% error rate may seem like a lot, but it is much smaller in comparison to other Fitbits and fitness trackers. The same study found that other devices have incredibly high error rates, some as much as 93%. This shows that the Fitbit Surge is much more accurate than other models, including the Fitbit Charge 2, Apple Watch, and more. 

Why Are Fitness Trackers Inaccurate? 

Given that Fitbit and other fitness trackers cost so much money, you are probably wondering why they are often inaccurate. The answer is rather simple. These trackers cannot do anything more than give an estimated guess at how many calories you are burning. 

Each fitness tracker is created with a certain algorithm that considers a variety of factors that impact calorie burn. This algorithm helps to guess how many calories you are burning based on these factors, but it does not give you a definitive answer to how many were burned. 

How Does Fitbit Track Calories Burned? 

So, what kind of factors does Fitbit use to estimate how many calories are burned? Let’s take a look at the most common factors used in these algorithms to estimate calories burned. 

Basal Metabolic Rate 

Your basal metabolic rate is how many calories you burn simply to maintain your vital body functions. Basal metabolic rate is different for every person, but it can be estimated based on your age, height, gender, and weight. 

Using the basal metabolic rate is the main reason why fitness trackers are so inaccurate. Not everyone under the same age, height, gender, and weight classifications has the same fitness level. As a result, their metabolism will not be the same. Due to this fact, the algorithm is automatically guessing calories on a data point that may not be true to your health. 

Let’s look at an example. Say that Person A is a 21-year-old female who is 5’3’’ and weighs 130 pounds, but she does not work out. Meanwhile, Person B is also a 21-year-old female who is 5’3’’ and weighs 130 pounds, but she works out nearly every day. 

These two individuals do not have the same basal metabolic rate because of their different fitness levels, but the algorithm would put them in as having the same basal metabolic rate. As a result, their estimated burned calories would not be accurate. 

Movement, Exercise, Heart Rate, Etc. 

As you already know, the point of a Fitbit is to track your exercise, movement, and heart rate. It’s pretty easy to understand that tracking motion is prone to a lot of error. 

For example, your Fitbit won’t pick up that you were walking as you push a shopping cart at the store. Conversely, your Fitbit may assume you are moving whenever you are just fiddling with the watch. 

From there, the Fitbit will estimate how many calories you have burned using the movement and basal metabolic rate. Given that both the basal metabolic rate and movement tracking can both be incredibly inaccurate, the number of calories burned will be inaccurate as well. 

How Does Fitbit Compare To Other Brands? 

Because of how inaccurate Fitbits are, you may be thinking about buying a different fitness tracker. Unfortunately, all fitness trackers are inaccurate and either underestimate or overestimate the number of calories burned throughout the day. 

As we mentioned above, the cheaper fitness trackers from the study were incredibly inaccurate when measuring how many calories were burned from running. However, they were more accurate when it came to estimating calories burned from walking. 

With this fact in mind, that tells us you don’t have to pay as much money for an accurate fitness tracker. If you plan to estimate your calories burned from walking, selecting one of the cheaper fitness tracker brands may give you better results. 

There are certainly reasons to opt for the Fitbit instead. For example, Fitbits tend to be more durable and come with more features. These features may help you to stay motivated and excited to workout, which can help you burn more calories, even if the Fitbit isn’t tracking them correctly. 

At the same time, the Fitbit Surge constantly ranks as one of the most accurate fitness trackers on the market. That’s because the most accurate fitness tracker was incorrect nearly 27% of the time, which is about the same error rate as the Fitbit Surge. In other words, the Fitbit Surge is more accurate than just about any other tracker on the market. 

Should You Still Use A Fitness Tracker? 

At this point, you may be tempted to throw out your Fitbit altogether. If it’s not accurate, what’s the point in using it? Although you certainly shouldn’t put all of your fitness goals in a Fitbit or another fitness tracker, they are still a great way to stay fit and healthy. 

In fact, fitness trackers can be a great tool to supplement in to your workout routine. It can keep you motivated to stay active and working towards your goal. You can set reminders and a number of other features to keep you sweating throughout the day. 

Because fitness trackers can be such a great supplemental tool, it’s definitely a good idea to opt for a model that comes with a number of additional features. These features will allow you to personalize the fitness tracker to your life and needs. As a result, you can best tackle your health and fitness goals. 

Final Thoughts 

Despite their expensive price, Fitbits are not very accurate at tracking the number of calories burned. However, no fitness tracker can accurately estimate these numbers since they are based on generalized guesses. In comparison to other fitness tracker brands, some Fitbits, especially the Fitbit Surge, tend to be the most accurate on the market. 

Just because a Fitbit is not completely accurate does not mean you should not use it. Instead, Fitbits are a great way to keep yourself motivated and excited to workout. Just keep in mind that the estimated calories burned is not completely accurate. Still, use your Fitbit as a way to stay motivated and excited to stay in shape. 

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