I've worn Whoop 4.0 for two years – here’s my review

If there’s one wearable that I get asked about the most in 2024, it’s Whoop. This screen-less, discreet band has captured the attention of consumers, thanks to its excellent marketing, popularity among elite sports stars, and sleek design.

I'm always eager to discuss it because it's a device that I've worn every day for over two years. 

I've continued to wear the Whoop 4.0 because it's one of the most insightful and actionable wearables available. It helps me improve my sleep, make positive choices, and build better habits better than any other wearable I've used. It's also the only wearable worth wearing in the gym.

However, despite its pricey monthly subscription, it's unlikely to be the only wearable many people will want to own. And that means compromises must be made.

With two years of new features added to Whoop 4.0, we've totally overhauled our review. It was originally published on 24 December 2021. Additional testing and reporting by Michael Sawh and Conor Allison.

Price

The Whoop 4.0 has a variety of pricing options. You can also opt to pay $399/£394 up front, which includes 24 months of membership at $16/£16 a month. 

Alternatively, you could choose to pay £234/$239 upfront, which works out to $19/£19 per month for 12 months.

Or you can just pay $30/£27 per month, which works out to £324 for the first year. You can check the best Whoop prices here.

That means that over two years, it costs the same as a high end smartwatch – so it's pricey. A lot of people will also want to use a Garmin or Apple device at the same time. As ever, you're paying for the algorithms and engineering here – not for the device itself. 

But it's worth noting that these features can be found on high-end Garmin devices – such as Garmin Fenix 7 (from $499/£559), Garmin Epix ($899/£749) or Forerunner 965 ($599/£599). 

- Read our Whoop vs Garmin guide for the key differences

Design

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A simple module wrapped in a fabric band, the Whoop 4.0 is pretty discreet. I usually wear it with an Apple Watch Ultra on the other wrist, or a traditional wristwatch, and it does a good job of being a companion without looking too conspicuous.

The standard band is black, but you can choose from various replacements on the official Whoop site – although they are fairly expensive. The bands can get dirty from workouts and day-to-day living, so having a second option is advisable. You can simply toss them in the wash when they need a clean.

You can wear Whoop away from the wrist if you prefer. You can purchase a bicep band, which improves accuracy on the upper arm. Additionally, various Whoop Body garments have spaces for the module against the skin of your arm, back, or waist. Although not endorsed by Whoop, I've had good results shifting the band to the upper forearm.

- Whoop 4.0 vs Apple Watch

Whoop 4.0 is 5ATM water-resistant, so you can take it into the pool or shower without worry. The band will need to dry out, but it does so quickly.

The battery lasts around five days and can be recharged via the supplied module. The charging module is also wearable, so you can place it on the band itself and walk around or sleep while charging, ensuring you never have to take the Whoop 4.0 off.

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A downside of Whoop not having a screen is the lack of real-time feedback. It doesn’t tell the time, and there are no notifications of any kind. However, most Whoop users won’t miss those features. There’s also no display for live workout stats, meaning tracking workouts isn't a major function.

One ‘smart’ feature, however, is the silent vibrating alarm – which can be set to trigger when you've reached a certain sleep goal or at a specific time. We found this feature useful and effective.

Core tracking features

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What Whoop does can be broken down into three distinct areas:

Sleep: Whoop tracks your sleep extensively and in-depth, and it's adept at removing wakeful periods from your sleep so you get a true picture of your rest. It's not sugar-coated, and helps you really focus and improve. It also monitors sleep need, calculated by comparing your actual sleep to your core needs, with any additional requirements from strain added on top. It's a tough task master.

Recovery: Whoop monitors HRV and offers a Recovery score indicating how well-rested and prepared you are. This is affected by lifestyle factors such as alcohol consumption, which can significantly impact your recovery score.

Strain: Whoop tracks the strain on your body from workouts and incorporates that into your recovery needs.

These three areas are the core pillars of the Whoop experience. The goal is to keep recovery in the green by getting good quality sleep. If you achieve that, you'll be well on your way to performing at your best.

What I love about Whoop is how sensitive these metrics can be. A single glass of wine in the evening can significantly impact the recovery score the next day. That same glass can also visibly affect your sleep quality data. So Whoop is adept at reflecting lifestyle choices in data – which can build more informed behavior (*willpower required).

This is supported by the Whoop Journal, which prompts you to quickly input factors like caffeine, alcohol, and other variables when you wake up in the morning.

Unlike when we first reviewed Whoop in 2021, elements tracked in the Whoop Journal are now analyzed to show the effect on your body. In our original review, we dismissed Journal as not being useful enough, but that has been addressed. Psychologically, the act of adding in your behaviors has a strong effect. 

My data shows that alcohol consumption usually has a -13% effect on my recovery. That’s significant. But the act of adding these factors to the Journal makes you accountable in a way that few wearables have achieved. As with many aspects of Whoop, it has a profound effect on your choices.

It's also worth shouting out Whoop Coach – the new AI service. The chatbot enables you to ask questions about your data or trends, and it will also pick out interesting insights on your data. I often ask it for my health data trends across time – or quickly as things like "when was my best sleep ever." It can also be used to query things like recovery food or questions on workout form. As it's provided at no extra cost it's a cool addition and makes Whoop even more useful.

Sleep tracking

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Whoop has become a benchmark for sleep tracking testing on Wareable and offers one of the best experiences, alongside Oura and Fitbit.

Sleep performance is displayed as a percentage of your sleep need, so it's not just about getting 8 hours every single night. If your sleep need is low, you can get away with a late night without Whoop scolding you.

Whoop also helps you ‘plan’ sleep, advising bedtime to ensure you get 100% of your sleep need, enough to ‘perform’ (80% recovery score) or just ‘enough to get by’.

The new Plans tab within the Whoop app also allows you to participate in challenges that benefit sleep. Typical challenges involve giving up screen time in bed or taking a hot shower before turning in. So there’s a holistic approach to sleep, which is refreshingly unique. It’s there if you want it, or you can keep it simple and just review your performance each morning.

Deep (SWS), light, and REM cycles are tracked every night, and your usual baselines are shown so you can see whether you got more or less than usual. Whoop will contextualize these too, suggesting reasons why they might be up or down.

Whoop also tracks the number of wakes per hour, breaths per minute, and efficiency – all shown against your personal normal baseline. It doesn’t feel like information overload, and the traffic light system makes it easy to glance over a night’s sleep.

These data points don’t usually reveal too much, but if you're getting sick, Whoop comes into its own.

Health Monitor

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Whoop introduced another tool with the Whoop 4.0 in the form of the Health Monitor.

It monitors five core metrics of your health: breathing rate, resting heart rate, blood oxygen, skin temperature, and heart rate variability.

All of these provide a solid overview of your well-being, covering signs of illness (any rise in breathing rate is a significant indicator of illness, as is skin temperature) as well as tiredness, stress, and hangovers.

Most days, this is just a panel of green data points that don't require a second thought. However, if/when you do get ill, it's an invaluable tool. Over the years, the Health Monitor has put me in tune with my body and its signals – and it's a great tool for monitoring your recovery from illness and understanding when it’s right to resume training, the gym, or spend an extra day in bed.

It can also theoretically help you spot when you might be getting sick, as some people's breathing rate will soar before getting sick. The clear traffic light system and heads up from the Whoop overview screen make it a useful part of the ecosystem.

It's one of my favorite parts of the Whoop ecosystem – and its taught me a lot about how my body responds to illness. I got hit by COVID shortly after wearing Whoop back in 2021 (screenshot above), and the way in which Health Monitor reacted – and how I felt – sold me on Whoop's accuracy.

Whoop will also offer you weekly and monthly performance reports, showing in-depth health trends. Its end-of-year report is always an eye-opener and a great way to realize how seriously the userbase takes its stats. I'm regularly in the bottom percentiles for most metrics, which is sobering.

Strength Trainer

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If you enjoy lifting weights, then the new Whoop Strength Trainer is a great addition. First, it helps you get credit for workouts in your Strain Score – which will help guide recovery. We wrote a guide on how to use Strength Trainer based on our experiences which goes into more depth than here.

But as a weightlifting newbie, it's helped me in the gym and guided me through some complex workouts. It's one of the smarter tools out there – regardless of your level, and we've just tipped it as the only gym wearable worth buying.

It's a smarter tool for building and following workouts in the gym than most wearables offer – and it's right there inside the Whoop ecosystem.

The criticisms of it are the same as we have for most of Whoop: it doesn’t help you progress your ability, overload your weights, or ensure that you’re working muscle groups optimally. It could be a much more effective tool, by tracking progression, or advising you when to up your lifts.

However, if you do log the weights used, it's helpful for remembering what you were lifting last time out. The interface is just a little fiddly – and it could easily be improved.

Stress Monitor

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Another addition to Whoop since we originally reviewed Whoop 4.0 in 2021, it will now keep tabs on daily stress.

We spoke to Whoop for a special podcast about the stress monitor, which helped us understand its intentions. But it’s still a tool that's fairly opaque and hard to use, based on over a year of use.

Stress Monitor will keep tabs on low, medium, and high stress – and will tell you how many minutes of high stress you endured for the day. This usually comes as a notification around 4 pm. You do get a good feel for what's normal, so if you have a high-stress day, you may choose to do something about it.

Personally, I have never opted to do something about it – but if you’re feeling overwhelmed, then that information is there. There are some guided breathing sessions in the Whoop app, although it doesn’t prompt or suggest these.

It’s a light-touch metric that hasn’t cut through for me, but it’s not annoying. 

My main criticism is that – like every ‘stress monitor – it’s not very good at linking specific events to high stress. So working out triggers requires you to do the hard work. 

Usually, the graph just looks like the tracking of a low-level earthquake, and I challenge anyone to infer much insight from the chaotic lines.

Workout and fitness tracking

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This is where the interest in Whoop will lie for a lot of people – and it’s often a surprise when I tell people that it's not a great workout tracking device.

I've demonstrated from my experiences that Whoop is a powerhouse when it comes to sleep, wellness, and readiness tracking – and is a brilliant partner for becoming the best version of yourself.

But many of the people interested in that side of things will also enjoy working out. And for that, the experience is… uninspiring.

You can track workouts in Whoop, of pretty much every kind. There’s automatic workout detection that will kick in for most energetic sessions (it usually misses my yoga class or captures the core 15 minutes) – but you can start tracking a host of workouts from within the app. You can also retrospectively tag workouts (see our guide).

If it's an outdoor workout, you can take advantage of GPS from your smartphone and it will be tracked with distance and map data – as well as heart rate data.

Whoop can also send workout data to Strava. If you let it auto-detect workouts then Strava will get a special graphic showing strain score (and heart rate/duration). If you track it properly, then the session will get GPS data and appear just as if you used an Apple Watch or Garmin.

As with any workout tracked via connected GPS, accuracy issues may arise if you pop your smartphone in a belt or clothing with a poor line of sight to the sky. But for occasional workouts, it does the job.

So it certainly gets the job done. But here’s where things get less desirable.

Workout analysis is minimal, so other than reporting the time and strain of the session, there’s nothing particularly interesting about reviewing your run/cycle/CrossFit session.

Whoop doesn’t record your personal bests or have any interest in analyzing performance, let alone tracking improvement over time.

For anyone with one eye on fitness levels, it falls well short of the likes of Garmin, Polar, or others. You can get that stuff if you let it push out to Strava Premium – but with the caveats listed above.

It's curious as most people will obsess over recovery data and sleep to be better at their sports, races, fitness, or life goals. But Whoop doesn't close the loop by informing you about whether you're improving in those areas. It's a big miss in our eyes.

Heart rate accuracy

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So if you do opt to use Whoop to track workouts – how does the heart rate accuracy stack up?

I've spoken to a number of Wareable testers who use Whoop and the consensus is that it’s not the gold standard for heart rate accuracy. But it also gets the job done.

In my own dedicated tests, the Whoop sensor does tend to report slightly lower heart rates compared to an EKG chest strap.

In our original review in 2021, Michael Sawh found that heart rate data could be “+/-10bpm out from by HRM-Pro chest strap.”

In 2024, comparing a hard spin class to a Garmin HRM-Pro in real time, we found that the early stages in lower heart rate zones (zone 2) saw some erroneous data from Whoop, which followed our 2021 testing.

But once we climbed through into zones 3 and above – I also found excellent accuracy. I quickly pushed my heart rate in one sprint from 160-190bpm, and Whoop dutifully followed. It topped out around 186bpm, typically a few bpm short of the chest strap – but overall produced decent usable data, after an initial fumble.

Positioning can be important, and I have found much better accuracy by moving it up the arm, using the bicep sensor. As a man with white skin, I live a charmed existence for optical heart rate monitoring – but have seen good results on the forearm.

As we asserted, the Whoop 4.0 is not an amazing workout tracker – and with no screen, it’s not fully designed to be used as a ‘live’ device in this way. I don’t have too many problems with the accuracy of its data for reporting the effort and strain of workout sessions – and baseline data for resting heart rate has always been on-point.

In short, heart rate accuracy is not the gold standard for micro-analyzing and guiding workout sessions in real-time – but Whoop isn’t really good for that anyway.