The health and fitness tracker industry is booming in 2025, but one name continues to stand out The Whoop 4.0. Marketed as a performance-enhancing wearable for athletes, high performers, and wellness enthusiasts, Whoop 4.0 promises deep biometric insights without the distractions of a traditional smartwatch.
But does it live up to the hype? In this Whoop 4.0 review, we’ll break down the following:
- Design & Comfort
- Key Features
- Performance & Accuracy
- Battery Life & Charging
- The App Experience
- Subscription Model
Do let’s dive into each of these in more detail below 👇
Design & Comfort:
Whoop 4.0 has a minimalist design with no screen! With no screen it allows users to focus on their health and fitness data through the app. This removes the distractions of constant notifications or a flashy interfaces. Like most if not all fitness trackers it’s designed to be worn 24/7.
One of the great things about the Whoop 4.0 It can be worn on the wrist, bicep, or even seamlessly integrated into specialised Whoop Body garments. This makes it different to other devices as it add more versatility and allows you to wear it where it’s most comfortable for you.
The Whoop 4.0 is lightweight and slim. It is also waterproof up to 10 meters, making it suitable for swimming, showering. However for me I take it off when I am showering as the band I have (the basic one it came with) takes a while to dry and I am not keen on the feel of it on my wrist when wet.
The fabric bands are breathable and adjustable. I dd find that it took a few dats to get used to how it sat on my wrist and getting the right tightness of the band. There’s also a wide selection of strap colours and materials, so you can choose the band that you like best.
Key Features:
There are a number of features that you get with the Whoop that help you dial into your health and fitness.
24/7 Health Monitoring
Whoop 4.0 is designed to collect your data around the clock, offering great insight into your body’s physiological state. It tracks;
- Heart Rate Variability (HRV), a key indicator of stress and recovery;
- resting heart rate
- skin temperature
- blood oxygen saturation (SpO2).
These data points are analysed to provide an overall view of your health. One of my favourite (and probably many others peoples) features is the Sleep Coach. It provides you with aa nightly recommendations for optimal sleep by telling you when you should be heading to bed. It also includes a Smart Alarm to wake you at the optimal time in your sleep cycle to you can set it to what time you want to be woken up.
Strain & Recovery Metrics
The Whoop 4.0 calculates a daily Strain Score based on your cardiovascular exertion. This score helps you understand how much effort you’ve put in and how that impacts your recovery.
The Recovery Score is taken from your HRV, resting heart rate, respiratory rate, and sleep quality. The recovery scores guide you in balancing effort and recovery, helping prevent overtraining and injury.
Whoop Journal & Coaching
The Whoop Journal allows you to log daily behaviours like caffeine intake, screen time before bed, hydration, and more. Over time, the app analyses this information to identify habits that improve or impair your recovery and performance.
Additional Features
- Respiratory Rate Monitoring: Detect early signs of illness or fatigue.
- Skin Temperature Trends: Useful for identifying stress, illness, or hormonal changes.
- Haptic Feedback: Includes gentle vibrations for the Smart Alarm feature.
These features work together seamlessly within the Whoop ecosystem to deliver science-backed, personalised insights that go beyond standard step tracking or calorie counts.
Performance & Accuracy:
Whoop 4.0 uses advanced sensors and refined algorithms to deliver detailed real-time data. Its performance in measuring heart rate, heart rate variability (HRV), respiratory rate, and skin temperature rivals that of some clinical-grade devices, making it a trusted tool among elite athletes and coaches.
The sleep tracking functionality is particularly impressive. Whoop breaks down your sleep into stages—light, deep, and REM—and provides a Sleep Score based on duration, consistency, and disturbances.
HRV tracking is central to the Whoop ecosystem, providing a strong indicator of recovery and stress levels. Unlike some wearables that only capture HRV sporadically, Whoop measures it during your deepest sleep phase, giving a stable, reliable snapshot of your autonomic nervous system’s function.
During physical activity, the Strain Score is calculated using continuous heart rate monitoring and the duration and intensity of exertion. This real-time feedback allows users to see whether they’re overtraining, under training, or hitting their sweet spot.
Battery Life & Charging:
The Whoop 4.0 has a 4-5 day battery life under regular use. One of the features that stands outs is the slide-on battery pack, which allows users to charge the device without removing it.
The battery pack is charged via USB-C and takes about 2 to 2.5 hours for a full charge. Once the battery pack is charged it slides onto the tracker and charges the device on your wrist unlike other wearable like the Apple Watch which need to be removed to charge.
The battery pack is also water-resistant, so you can wear and charge your Whoop even during workouts or in the shower.
The App Experience:
The Whoop app is where everything the tracker records is captured and where the data is put into user-friendly insights and recommendations. The app is divided into different sections;
- Strain
- Recovery
- Sleep
- Health Monitor
- Coaching.
Each area provides detailed information and personalised trends over time.
Strain and Recovery Dashboards are displayed daily allowing users to monitor their training. The Recovery Score is colour-coded (green, yellow, red) giving a quick and easy view of your readiness for exertion on that day.
The Sleep Coach tells you how much sleep you need and recommends a bedtime to ensure that you get the amount needed. You can then view your sleep stages, disturbances, efficiency, and latency in a format that is easy to understand.
The Health Monitor offers real-time information like your respiratory rate, skin temperature, resting heart rate, and blood oxygen saturation. You can set alerts if any of these change significantly from your baseline.
The Whoop also has a Journal and Coaching features which captures insights to your behaviours on a dally basis by analysing how factors like alcohol, caffeine, or meditation impact your recovery and sleep. Updating this daily builds a tool for habit tracking and that helps you identify what impacts your performance.
The Whoop you can join teams and compete in community challenges with other Whoop users for that bit of extra motivation. The app also integrates with the like Apple Health and Strava allowing you to sync your data other platforms.
Subscription Model:
The Whoop 4.0 will require you to pay a subscription fee similar to the Oura Ring. You do however get the device for free (well not really) as part of the subscription. You can choose to pay annual upfront which you will get discounted or you can pay monthly.
There are 3 plans that you can choose from;
- One
- Peak
- Life
The top plan (Life) will require you to have the new Whoop 5.0. I personally have the Peak Membership plan which is around £27 a month.
Final Thoughts:
If your goal is peak performance, recovery, and optimised health tracking, Whoop 4.0 is hard to beat. Its deep recovery insights, accurate health data, and distraction-free design make it a powerful tool for people that are serious about their health & fitness. The comfortable, screen less form factor is ideal for wearing 24/7 and the app delivers excellent actionable insights.
Pros:
✅ Deep recovery insights
✅ Screen less, distraction-free design
✅ Comfortable for 24/7 wear
✅ Accurate sleep and HRV data
Cons:
❌ Requires a paid subscription
❌ No built-in GPS or screen
❌ Learning curve for beginners
However, the need for a paid subscription, lack of GPS or screen, and a bit of a learning curve may deter more casual users or those on a budget.
If you’re committed to improving performance and can justify the ongoing subscription, Whoop 4.0 is one of the most comprehensive fitness trackers available on the market.