Whoop 4.0 Review: An In-Depth Fitness Tracker With Valuable Data Insights

Written by

Whoop 4.0 Review

The Whoop 4.0 is the newest fitness tracker from Whoop, a wearable technology company that focuses solely on using data to optimize human performance. After some customer feedback about its predecessor, the Whoop 3.0, the company released this smaller, more accurate version.

The Whoop 4.0 is designed around three major health metrics: strain, recovery, and sleep. The wearable sensor continuously tracks various data points, like your heart rate, breathing rate, oxygen levels, skin temperature, and sleep quality, to provide recommendations for improving the way you feel.

In this Whoop 4.0 review, we’ll go over the new design and the features of the latest fitness tracker, highlighting what we love and what we don’t. We’ll also discuss the app and the price, and answer the most commonly asked questions about the device.

Why Trust Us?

ACTIVE.com’s editorial team relies on the knowledge and experience of fitness and wellness experts including competitive athletes, coaches, physical therapists, nutritionists, and certified trainers. This helps us ensure the products we feature are of the highest standard. Collectively, the team has spent countless hours researching equipment, gear, and recovery tools in order to create the most accurate, authentic content for our readers. Customer satisfaction is also a key part of our review process, which is why we only feature products that are highly rated. More importantly, each member of our team is a fitness enthusiast. Fitness may be our job, but it is also our passion. Therefore, we strive to bring you products that we trust and would personally use.

By clicking on the product links in this article, we may receive a commission fee at no cost to you, the reader. Sponsorships and affiliate commissions help support our research so we can help you find the best products. Read our full affiliate disclosure here.

Whoop 4.0 Review

whoop 4.0 Review


  • Display: None
  • Features: Heart rate monitor, haptic sleep alarm, tracking for: sleep, fitness, respiratory rate, blood oxygen levels, menstrual cycle, skin temperature readings
  • Design: Lightweight knit band with clasp lever


What We Like

  • Highly accurate sleep data
  • Option to include menstrual cycle coaching
  • Provides recommendations based on strain score
  • Haptic sleep alarm
  • More comfortable than other fitness trackers

What We Don’t Like

  • Doesn’t have a screen to display data
  • Requires an ongoing monthly subscription
  • No design customization outside of band color

BUY: Whoop 4.0

Whoop 4.0 Design

One of the biggest changes in the Whoop 4.0 version is the design. This version is 33% smaller than the Whoop 3.0 and, because of that, it is considerably lighter. The Whoop 4.0 is very comfortable, even while sleeping.

It comes with a semi-stretchy knit band that sits flush on the skin. It doesn’t get caught on anything and it doesn’t cause the skin irritation common after continuous wear of other fitness trackers. It’s easy to adjust; you just have to pull on the strap a little bit.

While not totally waterproof, the Whoop 4.0 has an IP68 rating, which means it’s water-resistant in about 32 feet of water for up to two hours. Not only can you shower with it, but you can also swim in salt, fresh, and chlorinated water without any interruptions in the data tracking.

Unlike most other fitness trackers and sports watches, the Whoop 4.0 has no digital display at all. While this contributes to its understated look, you may prefer to see data pop up on the screen, especially when you are tracking your heart rate or time and distance during workouts so you may consider this a downside. For others, this may actually help you stay focused and undistracted during a workout, so it comes down to your personal workout style.

Because the Whoop 4.0 is meant for continuous wear, it comes with a battery pack that slides on and off the device to charge while you’re wearing it. You first charge the battery back—it takes just over two hours to reach a full charge—and then hook it up to the Whoop to get some extra juice while it keeps tracking your data. There’s an LED light on the side of the Whoop to let you know when the battery is running low so you can stay on top of it.

Whoop 4.0 Features

The Whoop 4.0 focuses on three major health areas: recovery, strain, and sleep. When you start your day, you get a daily recovery score from 0% to 100%, which is based on your heart-rate variability (HRV), resting heart rate (RHR), sleep duration and quality, skin temperature, and respiratory rate from the night before.

We found this to be a lot more insightful and accurate than the sleep scores of other fitness trackers. Not only does it incorporate more data points, it also gives helpful information about the best way to support your body that day, rather than just providing an arbitrary number.

As you go about your day, the Whoop 4.0 will start calculating a strain score that’s based on how much physical and mental strain you put on yourself. The app also provides a recommended strain score based on your recovery level from the night before. In other words, it will make recommendations about how much you should exercise and/or the level of exertion you should reach based on how "recovered" you are from the day before.

The strain score is calculated from the amount of time you spend in certain heart rate zones. This essentially measures how you’re reacting to stress and tension, whether it comes from something physical like exercise or mental like a heavy workload.

This is extremely helpful for making exercise decisions, but we found it even more useful for a prompt to take breaks during particularly stressful moments in the work day. If you notice your strain score creeping up too quickly, you can make it a point to take a step back and take some deep breaths to get your heart rate down to a better range. Over time, this can help you better manage your physiological reactions to stress, which may also boost your recovery and strain scores.

Sleep tracking is a big part of Whoop 4.0, since the quality of your sleep plays a huge role in your recovery score. It measures how much time you spent awake and in each of the four stages of sleep. You can also set sleep goals based on how you want to feel the next day, i.e. whether you want to "peak," "perform," or just "get by."

This adaptability is one of our favorite things about Whoop 4.0. The results and recommendations are always different, so they never feel generic. And instead of just providing a number or score, you’ll get recommendations about how you can translate that score to reach optimal performance.

In addition to these overall recovery, strain, and sleep scores, you can view individual real-time and historical data for heart rate, respiratory rate, blood level levels, resting heart rate, heart rate variability, and skin temperature. If anything looks off, you’ll get a potential list of reasons so you can make any needed changes.

It also has menstrual tracking and will adjust your strain scores based on how much your body can handle during a particular day in your cycle. We found this to be an extremely useful reminder that on certain days of your cycle, your body is just not equipped to handle excess strain from an intense workout. On these days, the Whoop 4.0 will recommend lighter workouts so you can give your body the break that it needs.

Of course, you can also use it as a regular fitness tracker and track individual workouts. It provides metrics like heart rate and calorie burn and it has GPS so it can follow along with outdoor workouts. We didn’t find this feature as accessible with the Whoop as on other fitness trackers because there’s no display on the actual Whoop 4.0. If you want to see heart rate or calories in real-time, you have to follow along in the app, which is pretty inconvenient.

Whoop 4.0 App

The Whoop 4.0 app is free with your subscription to the service. Setting up the fitness tracker takes seconds and the connection between the two seems solid. There were no problems with data reading, even when showering or swimming in the lake.

In our opinion, the app’s interface isn’t the most user-friendly. There’s a lot of information to look through and it feels a bit all over the place. If you mostly care about the strain, recovery, and sleep charts, they’re easily accessible on the home screen but you have to dig around for other data points and other weekly and/or monthly charts. The fitness tracking portion of the app also isn’t optimal, but it does the job.

Whoop 4.0 Price

Whoop is really a subscription service with a fitness tracker thrown in. Instead of just paying a flat fee for the tracking, you commit to a monthly, yearly, or 24-month subscription and you get the Whoop 4.0 included with that subscription. If you choose the monthly subscription, you have to commit to a 12-month minimum to cover the cost of the tracker.

Like most other subscription services, you save a little money overall if you commit to the longer-term plans. The monthly subscription is $30 per month. The annual subscription breaks down to $25 per month with a $300 upfront payment. The 24-month subscription comes out to $24 per month with an upfront cost of $480.

Who Should Buy the Whoop 4.0

Whoop 4.0 is intense, but it’s a great tool for anyone who wants to learn more about their body or the best way to optimize their fitness and recovery. If you have some experience with fitness tracking and you want to upgrade, the Whoop 4.0 is a good next step.

Whoop Accessories and Other Products


The Whoop 4.0 comes with a standard Superknit band that goes around your wrist, just past your wrist bone. There are additional color choices as well as themed three-packs that you can purchase separately, but they’re all the same stretchy knit material. There are also bicep bands and thicker upper arm sleeves, as well as Hydrosleeves—100-percent silicone, water-resistant bands that protect your Whoop when you’re in the water for extended periods of time.


In addition to extra bands, Whoop also introduced a Whoop Body line of clothing. It includes shorts, leggings, sports bras, compression tops, boxers, and women’s underwear, all of which are designed with an internal Whoop pod that can hold the sensor so you don’t have to wear it on your wrist. Each garment comes with recommendations for how to get the most accurate data. For example, one of the sports bras is recommended for light activity only, and not high-impact workouts.

BUY: Whoop 4.0

FAQs About Whoop 4.0

Is Whoop 4.0 worth it?

Because it requires an ongoing subscription, the Whoop 4.0 is definitely not a budget fitness tracker. But if you want in-depth health data and don’t mind viewing it through the app instead of directly on a watch screen, it’s worth it. It gives valuable insights on many different health metrics and provides useful recommendations on how to translate this data to reach your peak performance.

Is Whoop 4.0 accurate?

In my experience, the Whoop 4.0 is highly accurate as long as it’s tightly secured to your skin. I never question the validity of the data and the results match up to how I’m physically feeling almost 100% of the time.

Can I wear Whoop 4.0 in the shower?

Yes, you can wear Whoop 4.0 in the shower. However, it’s recommended that you take off your Whoop and wash the band and sensor with soap and water when doing so. You’re also encouraged to wash the skin on your wrist where the sensor makes contact for the most accurate readings.

How long does a Whoop 4.0 battery last?

Whoop estimates that the battery will last around four to five days on a full charge. In our experience it’s more like three to four days, depending on how it’s being used. On average, you can expect to charge it about two times per week.

The battery pack takes just over two hours to fully charge. Once that’s charged, you clip it onto the sensor and it will fully charge the Whoop one time.