Whoop 4.0 Review: Improved Accuracy Makes The Whoop Band A Useful Sports Tracking Tool

Whoop 4.0 is a huge improvement over 3.0. Heart rate tracking, both during workouts and while at rest, has become more accurate. Besides, tracking stress can be a useful way to ensure that you are training at the right level of improvement, whatever sport you have chosen. Sleep tracking is good too, although the overall recovery tracking falls short compared to other devices like the Oura Ring.

Rating ⭐⭐⭐ (3.5/5)


  • Improved accuracy of heart rate tracking
  • Track good sleep
  • Comfortable belt
  • Detailed insights for a wide range of stats
  • Smaller than Whoop 3.0


  • Doubtful recovery scores
  • No screen or GPS
  • Monthly subscription

Whoop Band is not your typical fitness tracker. It does not have a screen and focuses on two main measures: stress and recovery. Each night, the band tracks your sleep to give you a recovery score the next morning, and then each day gets a stress score based on how much activity you’ve done. The goal is to make sure your stress level aligns with how well you recover, and Whoop will coach you to achieve that.

When I tested Whoop 3.0, all of the insights it presented were undermined by inaccurate heart rate tracking, meaning that stress scores were wrong most of the time. The new Whoop 4.0 improves on the sensors in the range, becoming a more useful product in the process, although the trace recovery aspect is still not entirely reliable.

The bracelet also remains a fairly convenient product since it does not have a screen or GPS, so it cannot replace a sports watch. Instead, it’s best used in conjunction with another device, which may seem like overkill, especially considering Whoop costs £30 a month (although that price drops when you stick to a longer subscription).

what’s new?

The most significant change in Whoop 4.0 is the new heart rate sensor, which has five LEDs — three green, one red, and one infrared — compared to the two green sensors in Whoop 3.0. In addition to increasing the accuracy of heart rate tracking, the device can take measurements of skin temperature and blood oxygen saturation.

Another big change is that the new range is 33% smaller than the previous version, but the battery life remains the same at five days. Now you can also wear the sensor in more ways: The Whoop Body clothing line has sensor pockets so you can wear it at the waistband of your panty, underwear, or in a bra. I wasn’t able to try out the Whoop Body equipment, so I wore a Whoop around my wrist, forearm, and biceps when tested.


The Whoop 4.0 band is lightweight, waterproof, and comfortable for 24/7 wear. Even when wet after a shower, I found the band didn’t get annoyingly wet on my wrist or arms, and it dries quickly. You can wear it 24/7 thanks to the smart charger design; You charge a small battery pack that then slides into the bracelet to charge while you’re wearing it. The new Whoop battery pack is also waterproof, so you never need to take it off – you can shower while charging.

I found the Whoop 4.0 with its new, smaller band to be comfortable to wear. A sleeker design is always welcome if it’s not at the expense of battery life and the 4.0 lasted the same four to five days that 3.0 did when charged. Sometimes locating the battery pack charger after that period was tricky compared to just plugging in the band itself, but there were several occasions when being able to charge the band without removing it meant I could head straight for a run or other workout while I was wearing it rather than waiting for it to charge.

Track your stress and recovery

On the face of it, life is simple in the world of Whoop. You put your body under stress every day (up to a limit of 21), and every night you recover, with a 100% recovery rate in the morning. You can then use these two scores to judge your training: Pushing your stress beyond recovery levels in the short term will see improvements in your fitness, but you need to make sure you get enough rest and not overdo it for too long.

That’s all Whoop does. It will not record your step count or track the distance you covered in your run or lap. It keeps things relatively simple with these two degrees, even though there is a lot of data to back it up.

The degree of your stress is determined by your heart rate – the more stress, the more stress you put on your body. Stress mostly builds up when you exercise, but it can also arise from daily activity. The inaccuracy of the Whoop 3.0 heart rate monitor often overestimated my stress because the readings were too high when I wasn’t exercising.

This problem occurs more often on Whoop 4.0. When I wore the bracelet on my wrist, it would sometimes read a little higher than my actual heart rate and log some “fake stress” a day, but not so much that my stress scores were significantly affected. He also didn’t record the dummy workouts, which he did 3.0 regularly.

However, during my workouts, I found that I had to wear the band on my biceps to get reliable readings, and after a particularly bad run where the heart rate reading from the wrist was too high the whole time, I transferred the Whoop to my biceps permanently.

When I was in position there, I found that stress recordings are accurate over a long period, and you can even use Whoop as an external heart rate monitor to connect to your watch by setting it to broadcast your heart rate in the partner Whoop app.

Workouts are automatically tracked by Whoop Squad and when one is detected you’ll receive an alert to look at it in the app, prompting you to provide more information like what sport it was and how hard it was to find it. You can also track workouts manually by starting them in the app, but the automatic system works fine and not much can be gained by starting a session manually because Whoop Band doesn’t show any stats to look in the middle of a workout.

Each day you’re also given a suggested stress rating in the app to target, which is hard to do since Whoop lacks a screen and doesn’t provide any guidance during your workout. However, if you start a workout in the app, you can set your stress coach’s recommendation as a goal and work toward it if you’re always within sight of your phone. I’ve found that once you get a feel for how the degree of stress aligns with your workouts, you have a rough idea of ​​what you’re aiming for in your major sport. For example, as a regular runner, I developed a sense of what a Whoop fatigue score would give me from an easy 60-minute sprint.

The payback classification is more complex, and I found this half of Whoop to be less impressive. The outcome depends on how long you sleep, heart rate variability (HRV), resting heart rate, and overnight respiratory rate, with HRV being the most important factor.

To confuse things a bit, there’s also the app’s sleep performance score, which just covers whether you reached Whoop’s recommended hours of sleep that night. This has three settings: how much you need to be at your peak, how much you need to perform, and how much you need to get.

Overall, I ignored this somewhat simplistic finding, along with Whoop’s recommendations on sleep duration. I’m often told to sleep longer in the mornings to increase bedtime with a suggested bedtime after 11pm, when it’s more useful – as far as I know – and more practical – to sleep earlier if you’re looking to increase bedtime rather than lie.

The recovery result is much more beneficial, but I had several days when I did not feel consistent with the result that I provided. This contrasts with the traceability from the Ora ring and its degree of readiness, which are generally specific. While Whoop 4.0 always seemed to adjust to the times I fell asleep and woke up, I quickly discovered that I couldn’t rely on the degree of recovery as an accurate indicator of my body’s state each day.

There were times that were clearly out of control too, like the days after the COVID booster shot when I had side effects like muscle aches, cold symptoms, and night sweats. Although the band measured my skin temperature was 2°C above average, it still rated within my normal range on the Health Monitor dashboard, which also shows stats like HRV and resting heart rate .

On the first and second day after the knockout, Whoop gave me a low recovery score, but that was the case, and in the following days I was back to high recovery rates much more quickly than I felt it actually took it to recover. In comparison, the Oura episode required me to enter “rest mode” for a few days after the jab and clearly marked my elevated skin temperature as cause for concern, with a simple tip for rest.

All information recorded by Whoop is presented at least in an attractive manner within the partner application. This does a good job of presenting high-quality information such as key stress and recovery results on the homepage, so those looking to get in and out of the app can quickly get what they need. Then there’s more detail going deeper into the app for those who want to see their stats. You also get weekly and monthly assessments with graphs that show how well you’ve been able to manage stress and recover over time.

Should you buy it?

Once I moved it up my arm, Whoop 4.0 logged reliable enough data on the stress introduction, and as an avid runner I found the information useful and helped me create a well-balanced training plan. And while recovery tracking isn’t entirely accurate in my experience, it still provides a good guideline that you can use every day to assess your sleep.

Overall, Whoop 4.0 is an interesting product that can help highly motivated athletes manage their training, but it’s not perfect, and this is a problem given its price and competition. While the domain is free with a subscription, you pay £30 a month for Whoop on a six-month contract, although overall that price drops to £288 for a 12-month membership (£24 a month), or £324 for 18 months (£18 a month), spending a lot of money on a device you’re likely to use in tandem with a sports watch that offers similar data. Garmin has a body battery meter as well as training load and recovery tips, although its sleep tracking is often imprecise, while Polar has sleep tracking on par with Whoop and excellent training load analysis.

To make a more specialized product like Whoop worthwhile, it needs to be virtually infallible in the areas it covers, and in my experience that’s not the case with recovery tracking. Plus, on this spot is the Oura Loop, a more accurate sleep tracker that provides readiness scores to judge your training, in an app that does a better job of providing simple, actionable advice rather than the wealth of data Whoop just throws at you.

While I like the design of the range and Whoop 4.0 it offers more or less what you specify, it is not impressive that I would use it more than a sports watch or even along with it.

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