Whoop 4.0 Review: A Serious Tracker for Fitness, Health, and Life

Key Takeaways

  • The Whoop 4.0 is a comprehensive solution for tracking activity and sleep metrics with its various sensors.
  • The device provides valuable insights into the body’s daily activity and stress levels, helping users make informed decisions.
  • While wearing the Whoop 4.0 all day, every day is doable, it could bug some people during the night, but doing so lets it offer personalized instructions for achieving custom goals.

The Whoop 4.0 is not just a general fitness tracker for anyone. It’s a fitness tracker for those serious about improving multiple aspects of their lives. In that regard, I would suggest this device is more of a life tracker to help people gauge how well their daily lives are in balance—between sleep, stress, and activity.

Whoop 4.0 is easy enough to wear with useful information, but nearly everything about it, from charging to its hefty subscription, requires an individual to be motivated to collect the information the device gathers.

whoop 4
Whoop 4.0

$216 $239 Save $23

Whether it’s health, fitness, or sleep, the WHOOP 4.0 is a comprehensive solution to tracking multiple metrics thanks to its various sensors.


Health sensors
Optical heart rate (PPG) sensor, Pulse oximeter (Sp02) sensor, Temperature sensor, Accelerometer, Gyro sensor


Mobile payments

Workout detection

Metrics Measured
Blood oxygen, Calories burned, Duration of exercise, Duration of sleep stages, Hours slept, Hydration, Respiration rate, Resting heart rate, Skin temperature

Maximum Water Depth

Device Weight

  • Collects a lot of data for valuable insights about your body,
  • Overall comfortable to wear
  • Personalized instructions offered for achieving personal goals
  • Potentially high recurring monthly or yearly subscription cost
  • Charging module could be easy to lose

How Can Whoop 4.0 Help You Become More Active?

whoop 4.0 closed
Sergio Rodriguez / How-To Geek

I tried Whoop 4.0 at the opportune time. Although still attached to my Apple Watch Ultra 2, I have finally become disillusioned by Apple Watch’s lack of rest days and its inability to proactively help me decide how much to exercise throughout the week.

The big promise of Whoop 4.0 is that tracking all your vitals can help coach you into achieving some of your fitness goals. Whether those goals are wanting to start building activity habits or you already have a routine and want to push yourself to the extreme.

I fell in between those two sides but still wanted more guidance based on what my body may be trying to tell me.

The day I received the device, I got started with a full night’s sleep. Then I ran a 10K and pushed Whoop’s strain meter to near full the next day. The Whoop app advised me to go to bed a little earlier and get more rest to help my body recover. I did that, and then the next day, I ran a 5K. Over and over, this type of daily pattern continued. I exercised by running, and it tried to alert me to how much my body was ready for.

The Whoop 4.0 tracks respiration rate, blood-oxygen level, resting heart rate, heart rate variability, and skin temperature. It does this by using an optical heart rate (PPG) sensor, pulse oximeter (Sp02) sensor, temperature sensor, accelerometer, and gyro sensor.

Looking underneath Whoop 4.0 at its sensors
Sergio Rodriguez / How-To Geek

It’s not into tracking steps, which is fine because I’ve never cared how many steps I took each day. The device also doesn’t include GPS, so it didn’t know the route I ran or other GPS-related metrics. It was, however, able to auto-detect my running and add that to its knowledge of my fitness, so I didn’t have to do that pre- or post-run.

As I spent time with the device, I found it most helpful in understanding how much my daily activity was stressing my body and how sleep and rest (recovery) played into my future exercise activity.

Trying to Understand Recovery

Each day, I would check the Whoop app to see how well I slept. In the app, available for iPhone and Android, I would see sleep duration and other vital stats. All of these things are available as individual numbers, but the most helpful is the strain and recovery chart.

One line in the chart indicates the amount of work your body has been doing each day, while the other shows how it has been recovering by providing time to rest. The numbers were arbitrary at first, but it was easy enough to tell on a scale of zero to 20 how I was pushing myself or how much rest I was allowing my body to have.

On certain days, I felt more rested than it said I was, but in general, all the marks in the app seemed accurate. Not only do I wear an Apple Watch during the day, but I also use an Eight Sleep mattress cover, which tracks my sleep. The results weren’t the same because different processes were used, but they aligned and appeared close.

I preemptively saw helpful messages in the app about how much strain I should be doing each day. I liked that because the Whoop app is supposed to be the smart one. It should be the one to offer notifications about my strain and recovery process. The thing I didn’t understand was the times I ignored its recommendations for taking it easy. It would say that I exceeded my “Optimal Strain range” but temper it with, “But overreaching will help you get fitter over time.” The mixed signals were hard to understand. Still, in general, those regular, bite-sized messages were helpful. I am curious how helpful they would remain over multiple months and years.

The AI Whoop Coach

To go beyond short preemptive notifications and tidbits of informational data is the Whoop Coach—which is powered by AI. Think of it as a personal, fitness-minded ChatGPT if that helps. (Partly because this feature is a partnership with OpenAI.)

Once you get into the swing of asking it questions, it could be helpful. My biggest challenge, which I think will apply to a lot of people, is just not knowing what to ask. There’s a vagueness to all AI chatbots, which was present here too. Yes, there are prompts, but those only go so far.

When I finally made it past the prompts, I started small with the Coach and asked things like, “How long should I run tomorrow?” It answered by suggesting a 20-minute run to achieve a Strain of 15.9—and also giving a disclaimer that it was only a recommendation and to listen to my body.

Sweet. The app, through the device on my wrist, knew my body stats and was able to recommend physical activity tailored to me. But then another time, I asked it to help plan out my running schedule so I could hit 100 miles in the month of November, and it gave me more generic results.

It said to run around 3.3 miles per day, incorporating rest days, but do long runs on days my recovery score was in the green. That was much less helpful.

Whoop Coach isn’t a bad feature. I actually like the idea behind it and being able to find context for my activity data. But I think its effectiveness will vary widely from person to person, depending on how aggressive they are with using it and how creative or curious they are as well.

I know it would have been helpful to ask an Apple AI assistant about the running metrics Apple Watch introduced and whether my stride length was good or how I could improve that area to run more efficiently.

Wearing Whoop 24/7 Is Doable, But Not Ideal

charging whoop 4.0 while wearing it
Sergio Rodriguez / How-To Geek

Whoop 4.0 with its charger on top of it.

Even with all the metrics it tracks, the Whoop 4.0 device itself is pretty small. That’s good because the company wants you to wear it all day, every day—24/7. It’s positioned as you being able to wear it all the time, but I occasionally felt trapped by it.

It’s a wrist-worn device that’s wrapped in an interchangeable elastic band. Smartly, the company has put effort into making a large swath of colors and styles so people feel a sense of personality while wearing it. I didn’t care about the color aspect too much; I simply wanted a solid color so I wore a black band the entire time.

I ran with Whoop 4.0. I slept with it on my wrist. I kept it on every moment of my testing time. It was fine. I didn’t love sleeping with it on my wrist because I don’t like sleeping with any watch or rings on, but it was still manageable. I was motivated enough to get the sleep data that I put up with it. Monitoring stress throughout an entire day was also a reason to continually wear it. I had a hard time really identifying causes and correlations to my times spent in the high-stress zone (that were outside of exercise), but it was still helpful to get an idea of how much time was spent in each level of stress.

Whoop 4.0 Battery Life

Sergio Rodriguez / How-To Geek

Since the expectation is that you’ll wear the Whoop 4.0 all 24 hours a day, getting power to the device is interesting. The slim Whoop 4.0 device has a battery life of a few days. Then, when it runs low, there’s a little wireless contact charger that slides on top temporarily.

I likened the process to Air Force One being in an emergency situation where it can’t land, and so it gets refueled in-air by a second plane. The Whoop 4.0 always wants to be in the thick of the action, so every couple of days, it needs its emergency charge process to take place.

I didn’t mind sliding the contact charger onto the tracker for an hour or so when needed. It wasn’t as comfortable on as it was without it, but I didn’t hate the combination on my wrist. My biggest worry is setting the fairly small, proprietary charger down somewhere and losing it.

I tried to leave the Whoop 4.0 contact charger on my desk and recharged the device while I was working so I wouldn’t misplace it. When it’s not performing an emergency in-flight refueling, the little charger can be powered up itself with a USB-C cable.

Whoop 4.0 Price and Availability

The Whoop 4.0, with a 12-month subscription included, costs $239. You can buy a 24-month subscription with a device included for $399 directly from the company.

If you’re curious about trying the device and service but aren’t fully ready to commit, you can try it for free for 30 days by visiting the company’s website. You’ll receive a pre-owned tracker to use during the trial period.

Should You Buy the Whoop 4.0?

Whoop 4.0 tracker next to a blue elastic band
Sergio Rodriguez / How-To Geek

Whoop 4.0 tracker next to a blue elastic band

If you’re really interested in gaining unique insights about your health and fitness activity, the Whoop 4.0 is a fine device. It’s more specialized in that it doesn’t function as a clock or a music player or anything like that. Its job is to track your body’s data, and that’s all it’s focused on.

Because of its lack of dual functionality, I found the Whoop a little harder to be compelled to wear in addition to my Apple Watch—which handles notifications, podcast streaming, and lots more during my runs. Whoop’s $240 yearly subscription (or $30 a month) is also a major hurdle to consider. It most likely costs less than a personal trainer and might prove invaluable for the information it delivers, but it’s still not cheap. The Whoop Coach was intriguing, but I would need a lot more time with it before saying whether the feature ultimately pulled its weight or not.

If you’re feeling frustrated by a lack of fitness insight or want a little more guidance, then joining Whoop might be a viable solution. Even taking a one-time 12-month chance on it, instead of joining a gym, might provide a lot of value for the right people. It’s probably not going to be worth the investment, however, for anyone not motivated to follow the device’s prompts and alter some daily behaviors.

whoop 4
Whoop 4.0

$216 $239 Save $23

Whether it’s health, fitness, or sleep, the WHOOP 4.0 is a comprehensive solution to tracking multiple metrics thanks to its various sensors.


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