Fitbit Sense Review: Is the Tracking Inaccurate?

Fitbit Sense Review: Is the Tracking Inaccurate?


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The Fitbit Sense is one of the most popular wearable health tracking devices. Fitbit claims this product can help users “manage stress” and “put heart health first.”

But is Fitbit really proven to help users manage stress or is this just a marketing claim? Is the device proven to support heart health? How do real users rate the benefits and experience of Fitbit Sense? And what retailer sells the device for the best price?

In this article we'll answer all of these questions and more as we analyze medical studies on Fitbit and its underlying technology to give our take on whether Fitbit Sense is likely to help users manage stress and support heart health, or if it's a waste of money.

We'll feature real, unsponsored user reviews of the brand and provide a cost comparison to show which retailer sells Fitbit Sense for the best price.

Can Fitbit Sense Reduce Stress?

Fitbit claims their device can help users manage and reduce their stress levels through an electrodermal activity (EDA) sensor. This sensor detects for increased sweating as a stress signal, as explained in the informational video below:

EDA is clinically shown to track changes in stress levels, and may help reduce a user's overall stress by motivating them to take action when they're passively stressed.

The first version of Fitbit Sense only tracked stress when a user directed it to, but it appears that Fitbit Sense 2 has the capacity to track stress passively 24/7.

This is a huge functionality upgrade because by tracking stress passively, the device can alert users to meditate or engage in breathing exercises when they weren't even aware they were stressed, which can improve overall health.

For this reason alone we'd recommend Fitbit Sense 2 over the original Fitbit Sense.

A 2023 medical review analyzed data on the accuracy of wearable EDA devices, and confirmed their accuracy: "Wearable EDA sensors are promising in detecting perceived stress."

Before analyzing the effects of Fitbit Sense on heart health, we'll feature some real user reviews in the next section.

Real Users Review Fitbit Sense

A YouTube creator named "Hayls World" reviewed Fitbit Sense in a video that includes an unboxing, an overview of features and a comparison to other health tracking devices:

A YouTube creator named "TLD{R}eviews" explains why he returned his Fitbit Sense:

Can Fitbit Sense Improve Heart Health?

Fitbit suggests that their device can support heart health. The Sense has electrocardiogram (ECG) technology that can track heartbeats and notify users of early signs of a condition called atrial fibrillation (afib).

It’s extremely important to note that the ECG does not appear to work passively in the background like the stress tracking, and instead only works when users proactively open an ECG app and place their fingers on the device for 30 seconds.

This is important because, beyond being an annoyance, one of the main theoretical benefits of biometric devices is that they run 24/7 and provide early alerts about symptoms that users wouldn’t have thought to check, which can be valuable for further medical testing. 

If a user needs to proactively open the ECG app every day to test for afib, compliance will likely be lower. It will also be significantly inferior to a solution that provides constant passive tracking, which would result in a larger amount of data and potentially more accurate results.

clinical trial published in the Journal of Sports Sciences compared heart rate tracking accuracy from various commercial tracking devices, including the Fitbit. The researchers found that the Apple Watch was significantly more accurate than the Fitbit.

Relative error rates (RER) from the Apple Watch ranged from 2.4% to 5.1%, while RER from the Fitbit ranged from 3.9% to 13.5%. This test used the Fitbit Charge HR 2 device rather than the Sense, but this information still seems relevant for prospective customers.

A 2020 medical review tested wrist-worn heart rate monitors for atrial fibrillation and concluded that “further improvements in device technology are needed before integrating them into the clinical management of rate control in atrial fibrillation.”

The researchers concluded that the devices, including the Fitbit Charge HR, were not accurate enough to provide reliable medical data.

Fitbit claims in the heart health section of their website that the Sense is “validated in a clinical study to provide accurate results,” however there is no citation to this study and we can't find it.

We're unconvinced about the ability of Fitbit to support heart health, and find the research backing for the device's stress tracking to be more significant.

But what retailer sells Fitbit Sense for the best price? We'll review in the next section.

Where to Buy Fitbit Sense for the Best Price

Fitbit Sense is sold at a variety of online retailers. Here's a price breakdown at the time of updating this article:

Fitbit Sense

Brand website: N/A

Amazon: $172.56 (free shipping, link)

Walmart: $142.50 (free shipping, third-party seller, link)

Fitbit Sense 2

Brand website: $299.95 (free shipping  link)

Best Buy: $299.95 (free shipping link)

Amazon: $299.95 (free shipping link)

Walmart: $289 (free shipping, third-party seller  link)

The original Fitbit Sense doesn't appear to be sold on the brand's website anymore, and is cheapest on Amazon.

The Sense 2 is slightly cheaper at Walmart than at other retailers, but it's sold by a third-party seller which may increase the risk of counterfeit product.

Why Was Fitbit Sued?

Fitbit has faced several lawsuits since the company's inception.

In 2022, the company was sued over allegations that the devices burned some users' wrists, according to Reuters.

The lawsuit alleges that Fitbit customer service in some cases referred to the burns as "hygiene issues" or "skin allergies."

In 2016, a lawsuit was filed against Fitbit alleging that the device's heart rate tracking is inaccurate.

At the time of updating this article, we're unable to determine the outcome of either lawsuit. We'd imagine that the heart rate tracking has gotten more accurate since this lawsuit given technological advances, but as we highlighted in the heart rate section, we still have concerns about the accuracy of Fitbit for any heart-related test.

Fitbit Sense 2 vs. Versa 4

Fitbit Versa 4 is another smartwatch sold by the brand, and is currently $100 cheaper than Fitbit Sense 2 ($199.95 vs. $299.95).

Only the Fitbit Sense has the EDA stress monitor and the ECG heart rate monitor, so it seems technically superior and worth the money for those who can afford it.

We can’t identify any clear benefits of the Versa 4 over the Sense 2 other than cost, so for consumers set on purchasing a Fitbit we’d recommend the Sense 2.

Fitbit Sense vs. Apple Watch

The Apple Watch technology appears to be superior to Fitbit technology in terms of heart rate monitoring, as evidenced by the previously-linked medical study. We believe the Apple Watch 8 is the better choice for consumers looking specifically for heart rate monitoring and afib risk.

The Apple Watch 8 also passively tracks blood oxygen levels. While this is an interesting novelty and may appeal to some users on a purely technical level, there doesn’t appear to be much medical evidence for the benefit of blood oxygen tracking for the everyday consumer.

Both the Apple Watch 8 and the Fitbit Sense track sleep data. This can be valuable to users, because understanding sleep quality can help you optimize it (or seek medical attention such as a sleep study that can detect conditions impacting sleep).

An extremely thorough medical review on wearable technology for tracking sleep analyzed data from nine different devices and found that the Fitbit was the most accurate for tracking total wake time (TWT) and the third-most accurate for tracking total sleep time (TST).

A wearable ring called Oura which we recently analyzed in our Oura Ring reviews article was the most accurate for tracking TST.

We can't find any medical studies comparing the sleep-tracking capabilities of the Fitbit Sense against the Apple Watch 8, so we recommend the Apple Watch overall given its potentially increased accuracy in heart tracking.

Fitbit is a much better choice for budget-conscious consumers, as the Sense 2 only costs $299.95 while the Apple Watch 8 costs around $450.

Pros and Cons of Fitbit Sense

Here are the pros and cons of Fitbit Sense in our opinion:

Pros:

  • Afib data may be useful for preventative healthcare
  • Mostly positive customer reviews
  • Passive stress tracking
  • May reduce stress levels over time
  • Cheaper than most competitors

Cons:

  • Heart rate data may be inaccurate
  • May not be necessary for otherwise healthy individuals
  • Unlocking additional features requires monthly subscription

Fitbit Sense FAQ

Is Fitbit Sense Waterproof?

Fitbit claims the device is water-resistant up to 50 meters in a help article. The band may be damaged in water if it’s made from leather, metal or woven materials.

Users planning on swimming with their Fitbit should likely purchase a silicone band, which the company calls Sport Bands, as these are less likely to be damaged by water.

What Was Fitbit Sense’s Release Date?

According to Wikipedia, the Fitbit Sense was launched in September of 2020.

Does Fitbit Sense Track Blood Pressure?

Fitbit Sense doesn’t currently track blood pressure, but the company announced in April of 2021 that they’re piloting studies on a novel way to passively track blood pressure without the need for the traditional arm cuff.

If they succeed, this would be a revolutionary breakthrough because significant blood pressure fluctuations throughout the day can make once-annual annual checks relatively inaccurate.

Stay up-to-date on our research reviews

Conclusion

The Fitbit Sense appears to provide good value for its price.

The company has significantly improved its stress testing between Fitbit Sense and Fitbit Sense 2, as the newer model can now passively test stress levels throughout the day and alert users when they may need to take a break and de-stress.

We believe the stress tracking mechanism is the most valuable aspect of Fitbit, as the underlying technology is clinically shown to work, and this can support improved long-term health. 

We haven't come across much convincing evidence on the accuracy of Fitbit's heart health tracking, and some medical studies cited in this article suggest that the brand's devices are not accurate enough to be useful.

We would recommend Fitbit Sense 2 over Fitbit Versa 4, because the Sense has the valuable stress tracking.

We would recommend Apple Watch 8 over Fitbit Sense 2, because the Apple Watch's heart health tracking is more impressive in our opinion (though the device is also significantly more expensive).

Walmart currently has the best price on Fitbit Sense 2, although the listing is maintained by a third-party seller so it may be safer to buy directly from the brand's website.