We liked the Whoop 3.0 when we reviewed it last year, but the Whoop 4.0 ($288 per year) takes an unexpected step back: We tested three separate units, and they each gave us inflated heart rate readings and falsely detected activities. That’s disappointing, because the new version offers some promising upgrades over the previous model. Namely, it can track your blood oxygen saturation (SpO2) level and body temperature, both of which can reveal early warning signs of COVID-19. And although the fitness tracker still has an awkward, screenless design, it’s smaller than its predecessor, offers haptic alarms to silently wake you up, and comes with a waterproof battery pack that can charge the tracker while you wear it. But given the issues we experienced in testing, we recommend you look to more affordable and feature-rich alternatives, such as the Editors’ Choice award-winning Fitbit Charge 5 ($179.95).
Smaller, With a New Sensor Array
The Whoop 4.0 retains the design of the previous model and measures 1.7 by 1.1 by 0.4 inches (LWH) including the clasp. Its sensor module is just as wide and tall as the previous version, but it’s a bit shorter; Whoop says the 4.0 is a third smaller overall.
New sensors can track two metrics the Whoop 3.0 can’t, including your overnight blood oxygen saturation and body temperature. In light of the ongoing COVID-19 pandemic, these two metrics are valuable, as they can help you gauge whether a hospital visit is necessary.
Despite the Whoop 4.0’s slimmer profile, I’m not a fan of the design. In my review of its predecessor, I said it “stands out like a sore thumb,” and that hasn’t changed. It’s still too wide to be worn alongside a watch on the same wrist.
That said, the Whoop 4.0 is lightweight and generally comfortable to wear 24/7, even when sleeping. On one occasion, however, my unit got a bit warm, irritating my wrist and leaving a red mark on my skin. The only other wearable I’ve tested that caused significant skin irritation is the Fitbit Inspire 2.
While comfortable, the included SuperKnit wristbands are a bit impractical. This device was originally designed for professional and college athletes—people who sweat. So it’s bewildering that Whoop has stuck with a fabric band design that absorbs moisture and takes a fair amount of time to dry. After sweaty hot yoga sessions, my Whoop 4.0 SuperKnit band is always soaking wet. The last thing I want to do after a post-yoga shower is put on a wet, sweaty band.
I discuss Whoop’s pricing in the next section, but you get the sensor module plus one black SuperKint wristband for free with a membership. The company sells additional SuperKnit bands in a range of colors (starting at $49), a silicone Hydrosleeve meant for swimming (two for $12), as well as bicep bands ($54) if you prefer to wear the tracker higher up on your arm.
Alongside this new model, Whoop released a line of pricey garments that feature a hidden pocket to securely hold your sensor module in place, so you don’t have to wear it on your wrist. The Whoop Body collection includes sports bras, shorts, leggings, compression tops, bralettes, and boxers. At $79 for a sports bra and $109 for leggings, the prices are in line with premium athleisure brands such as Lululemon. Whoop didn’t send me any of these garments, so I cannot comment on their quality.
The 4.0 has a new fast-link slider that Whoop says makes it easier to change out the bands, though I still find the strap a bit difficult to manage. Expect to spend some time fumbling around with the product as you learn how to swap out the band, close and unclose the clasp, and slide on the charger.
The external battery pack charger (which comes in the box) slides onto the tracker and lets you juice it up while it’s still on your wrist. And unlike the previous model, the new battery pack is now water resistant up to 3.2 feet for as long as two hours. The Whoop 4.0 sensor module carries an IP68 rating and is water resistant to depths of 32 feet for two hours.
Whoop says the latest model offers the same five-day maximum battery life as its predecessor (depending on usage). Most of the time, my unit runs low on battery after about four days, which isn’t terribly impressive. For comparison, the Oura Ring, another screenless (and smaller) health tracker, lasts six full days on battery before running low. The Whoop’s battery life also falls short of the Fitbit Charge 5 and the Amazon Halo View, which last around a week on a charge despite their AMOLED displays.
An Ongoing Investment
The Whoop Strap isn’t just a one-time purchase. Instead of paying one lump sum for the hardware and getting its accompanying software features for free, as is customary with most fitness trackers, here it’s the other way around. The company offers its tracker for free with the purchase of a membership, which gives you access to the app.
Whoop offers three pricing options: $30 per month (with a six-month minimum commitment), $288 per year (which works out to $24 per month), or $324 for 18 months (which breaks down to $18 per month). The company offers a 30-day return policy, so if the product doesn’t meet your expectations, be sure to return it within a month for a refund (minus shipping costs).
The Whoop’s $288 annual price is a tough sell, especially when you consider that trackers like the Fitbit Charge 5 monitor the same key health metrics including your activity, blood oxygen saturation, heart rate, heart rate variability, respiration rate, sleep, and skin temperature. The Charge 5 also features a color touch screen, a built-in GPS, and an electrocardiogram (ECG) app, none of which you get with the Whoop 4.0.
Whoop’s membership gives you access to your health metrics; daily personalized training and sleep guidance; weekly and monthly performance assessments; and community leaderboards. Like the Whoop 4.0, the third-generation Oura Ring and the Amazon Halo View also require a monthly membership fee to access most of their features.
The Whoop 4.0 stands out for its detailed performance assessments, which uncover trends to help you make sense of your data (you can even export this data as a PDF), but its competitors offer more value. Oura’s membership, for instance, gives you access to a library of guided audio meditations to help you de-stress and prepare for sleep. The Amazon Halo membership is the most feature-rich of the three, with a growing library of healthy recipes, meditations, and workout videos.
Over a year, the Oura costs more at $334.94 ($299 for the base model ring, plus $5.99 per month for a membership after a six-month free trial) and lacks a few Whoop 4.0 features, including haptic alarms and the ability to broadcast your heart rate to other devices, but the tracker is much more stylish and discreet (and actually costs less overall if you use it for longer than a year). The Amazon Halo doesn’t track your respiration, but at just $79.99 (which includes a one-year trial membership), it’s a much more affordable tool for those starting on a health journey.
Like its predecessor, the Whoop 4.0 only integrates with Strava and TrainingPeaks. It isn’t compatible with Apple Health or Google Fit.
Tracking Early COVID-19 Warning Signs
In my review of the Whoop 3.0, I detailed its strain and recovery scores, so I won’t reiterate them here, but they are still a key part of the app experience. Every morning, I’m eager to check my recovery score to see if it’s in the green (67% or above). Striving for a sufficient recovery score motivates me to stop scrolling on my phone at night and get to bed earlier.
For the new model, Whoop adds a new Health Monitor section in the app that makes it easy to view your latest metrics and whether they’re within your baseline range. Now, in addition to checking my recovery score each morning, I always visit the Health Monitor. When you tap into this section, it shows your current heart rate, as well as the previous night’s readings for your respiration rate, SpO2 level, resting heart rate, HRV, and skin temperature. Here, Whoop also highlights any concerning readings in red or yellow, so you can keep a closer eye on them.
While testing the Whoop 4.0, I experienced a COVID-19 breakthrough infection, and the wearable picked up on indications of my illness. The same day I started feeling symptoms (four days before my positive test), the Whoop Health Monitor alerted me about a spike in my resting heart rate–120bpm, when my usual range is between 51 and 54bpm. At the time, I assumed it was an erroneous measurement, but looking back, it might have been an early warning sign. The next day (three days before my positive test), it warned me of a low SpO2 reading–88%, when my usual range is between 95 to 100%. Four days after my positive test result, when I was still feeling symptoms, the Whoop Health Monitor warned me about an elevated respiration rate–15.7rpm, when my usual range is between 14.1 and 15.5rpm. Fortunately, I’m on the mend, and my health metrics have all been within their normal range for the past few days.
The Whoop 4.0’s overnight metrics, including SpO2, respiration rate, resting heart rate, and heart rate variability, are generally on par with the Apple Watch Series 7. The Series 7 doesn’t measure your skin temperature, but it offers on-demand SpO2 readings, while the Whoop 4.0 only measures your blood oxygen saturation at night while you’re sleeping.
One night, for example, the Whoop 4.0 said I had an SpO2 level of 96%, a respiration rate of 14.5rpm, a resting heart rate of 51bpm, an HRV of 68ms, and +1.7-degree skin temperature (from baseline). The Apple Watch Series 7 said I had an overnight SpO2 level of 97-100%, a respiration rate range from 12.5 to 18.5bpm, a heart rate range from 44 to 59bpm, and an HRV of 67ms.
The new haptic alarm feature, which wakes you up with a gentle vibration, works as advertised, but is a bit hard to find. To enable it, navigate to the Coaching section of the app > Sleep Coach. Here, you can set an exact wake-up time or select from two other options: Sleep Goal (which wakes you up once you hit your sleep goal) or In the Green (which wakes you up when you reach a sufficient recovery score). In testing, the haptic alarm successfully jolted me out of my slumber. In my half-asleep state, I found it a bit difficult to stop the vibration, which woke me up more. To stop it from vibrating, firmly double-tap the device; otherwise, it will automatically stop after 30 seconds.
Concerns About Accuracy
When manually tracking a workout via its companion app, the Whoop 4.0’s fitness data is generally accurate compared with the Apple Watch Series 7. For a 20-minute indoor cycling workout on the MYX II, which I’m currently testing for an upcoming review, the Whoop 4.0 said I burned 189 calories, had an average heart rate of 154bpm, and maximum heart rate of 187bpm. For the same workout, the Series 7 said I burned 182 calories, had an average heart rate of 166bpm, and a maximum heart rate of 187bpm. Because the Whoop 4.0 lacks a screen, you must start and stop tracking an activity via the app, which is a bit cumbersome.
The Whoop 4.0 can automatically detect and log certain activities, but this feature was unreliable in testing. With the activity detection feature enabled, the Whoop should automatically log workouts when your heart rate is elevated for at least 15 minutes. In testing, it has correctly tracked hot yoga, hiking, and indoor cycling workouts.
Unfortunately, Whoop’s heart rate readings are sometimes way off, and cause the device to falsely log activities that didn’t happen. One morning, while I was getting ready for work and not exercising or exerting myself, the Whoop erroneously tracked a 22-minute activity, reporting an average heart rate of 181bpm and a maximum heart rate of 201bpm.
I test a lot of fitness trackers and have never seen my heart rate get that high. Indeed, over the past year, my maximum heart rate was 189bpm, according to the Apple Health app.
After this incident, I figured my review unit was defective, and Whoop sent me a new one. Unfortunately, the replacement tracker also reported inflated heart rate readings and falsely detected activities multiple times. To give Whoop the benefit of the doubt, I asked for a third unit; it suffered from the same problems.
In the two months I’ve been testing the Whoop 4.0, it automatically logged more than a half-dozen workouts that didn’t occur. And, in at least two instances, it tracked a workout even when I wasn’t wearing the band. For instance, when the tracker was sitting on my bedside table, it automatically tracked an hour-long activity, reporting my heart rate at around 200bpm the entire time.
I never experienced such issues when testing the Whoop 3.0. A Whoop spokesperson says an inflated heart rate can occur if your 4.0 band is too loose and the sensor is exposed to natural light. Tightening the band or moving it up to your bicep may resolve the problem, the company says. Obviously, wearing it on your bicep isn’t a 24/7 solution for comfort reasons.
If you experience problems with your unit, the company also recommends ensuring you have the latest Whoop firmware installed (navigate to Device Settings > Advanced > Firmware Check), and the latest version of the Whoop app. If you still experience problems, a reboot may help (navigate to Device Settings > Advanced > Reboot device, then reconnect the tracker via Bluetooth). In the app, you can also text with Whoop’s Membership Services team.
Contrary to my experience, a spokesperson tells me that recent updates “have continued to focus on improved wear detection and we’ve found members reporting (and through our validations) that the 4.0 heart rate accuracy has been better overall than 3.0.”
On a more positive note, the Whoop 4.0 has no issues pairing with smart fitness equipment. It automatically connected with the NordicTrack Vault smart strength machine and the MYX II smart stationary bike, using their displays to show my heart rate while working out.
Aesthetic and Athletic Shortcomings
If you don’t mind how it looks and aren’t particularly worried about tracking fitness metrics, the Whoop 4.0 can help you keep an eye on your sleep, overall recovery, and important health levels such as your blood oxygen saturation, respiration rate, and skin temperature. But when it comes to screenless health trackers, we prefer the third-generation Oura Ring, which has a sleeker design, longer battery life, and gives you access to a library of stress-relieving meditations. And while not as discreet, the $179.95 Fitbit Charge 5 is our top pick for fitness trackers with a display, with advanced features including the ability to measure small electrical changes in your skin’s sweat level to track your body’s response to stress, and an electrocardiogram that checks for signs of atrial fibrillation. Most importantly, both of these trackers reliably delivered accurate results in testing.
