If you work out a lot and want a fitness tracker, then the Whoop 4.0 band could be for you.

It is a simple device that tracks heart rate, skin temperature, and movement but doesn’t spit out step counts and the like as you would with a Fitbit or similar. Instead, it asks that you wear it over several weeks to build up a picture of your fitness – measured in strain and recovery.

The Whoop itself is free but you must spend at least $30/£27/€30 per month on a service subscription, although you can cancel at any time. That might be affordable for sport star advocates like golfer Rory McIlroy or footballer Virgil Van Dijk, but for normal people that is a high price to ask, and you only save by paying for one or two years upfront.

Fitbit Premium, for example, is $9.99/£7.99/€8.99 per month.

The Whoop 4.0 goes about fitness tracking quite differently from other popular devices by helping you work out when your body is ready, but it will end up falling short for you unless you work out a lot and want to obsess over your recovery data.

Design & Build

The Whoop 4.0 is a simple small pebble of a device that gets hidden by the removable strap and buckle it clips into to sit on your wrist.

That’s it. There’s no display, no speaker, no microphone. It’s a little slip of black curved plastic with a heart rate sensor on the back so sort of looks like you’ve got a watch on the underside of your wrist.

It’s the colourful straps available that have helped popularise Whoop among star athletes and regular folks alike, from all-black to rainbow-rose gold-fluro looks.

The bands are also very expensive. The black strap comes as standard but if you want to buy another, they cost either $49/£44/€49 or a crazy $99/£84/€90 for one with plated gold or platinum coating. It’s just a fabric strap with a buckle!

Putting the Whoop device itself into the hooks isn’t too fiddly but it’s a faff if you get the straps on the wrong way around. It’s comfortable to wear all day and night which is good because that’s what Whoop wants you to do.

I wore it in the shower a couple of times but the fabric strap stayed wet for hours, so that became the only time I took it off, as you can charge the band while wearing it thanks to the clever charger accessory that comes in the box.

Henry Burrell / Foundry

Fitness & Tracking

I’ll get this out of the way properly, the Whoop 4.0 does not record your step count.

The main thing to know about the Whoop 4.0’s tracking is that you won’t get much out of it unless most of your workouts are cardio heavy. The only sensors on a wearable are the five LEDs, four photodiodes, and a body temperature sensor, which handle heart rate and changes in electrical temperature in the skin and body.

This means you get all-day heart rate monitoring, though it’s only really surfaced to you in the Whoop app when you record a workout or look at your sleep data.

You can wear the tracker either in one of the aforementioned bands or in an item of Whoop’s branded clothing. I tested out the Any-Wear shorts, which are well-made and have a slot to put the tracker in the seam to rest the sensors next to your skin. The data from exercise was accurate, and Whoop also sells sports bras and other gear.

Henry Burrell / Foundry

I found I would need to exercise for at least two hours a week to get useful insights though, as the whole Whoop experience is built around measuring strain and recovery – the former recording cardiovascular strain on a decimal point scale that goes up to and over 20 (ie over 100%), and the latter recording your recovery as a percentage. The app will let you know if it thinks you are ready to train again, or if you should have a rest day.

Strain is calculated by measuring how long you spend in different heart rate zones, with the tracker also considering what your maximum heart rate is while exercising. For me, it says strain between 14 and 17.9 is considered strenuous, and I hit these numbers on longer runs and when playing football.

A day after an hour of five-a-side and my recovery was at 30% and the app advised me to chill out, which I gladly did.

Recovery is worked out from heart rate variability and resting BPM, respiratory rate, and length of sleep. Though Whoop spits out a proprietary strain score, it doesn’t do that for sleep and instead tells you when you should go to bed. It bases this time on how much sleep it thinks you need to recover and what time you tell the app you need to get up.

Henry Burrell / Foundry

The problem with Whoop is it only really accurately reflects your recovery when activities are cardio based, which works for my running and football. But it can’t reasonably detect levels of strain in strength training, so you could have done a hard weights session and feel knackered the next day but the app will say you are ready to go again because your heart rate may not have consistently spiked during the workout.

Running data is also quite simple and with no GPS built-in you have to take your phone with you to get routes tracked. I personally don’t look for intricate data on runs, preferring to log them but not obsessed with the data. A dedicated running watch like the Polar Pacer will be much better for runners who want to dive into granular data.

I ended up enjoying the sleep data insights, which accurately flagged that I was getting ill thanks to an overnight rise in skin temperature, and because my workouts are mainly cardio I found the recovery data useful. But at the same time, I was frustrated with the limitations of Whoop, and the fact you need to wear it 24/7 to get the most out of it. You might see this as an advantage over competing bands, but if I don’t wear it for three days, the hole in my data is more noticeable than other platforms like Garmin’s or Polar’s.

Henry Burrell / Foundry

Software & Features

The Whoop app has a steep learning curve but once I was used to it I found it useful.

As mentioned, I like the sleep data and you can also journal in the app, answering a wide ranging number of questions that take in alcohol and caffeine consumption, acupuncture, air travel, bloating, if you’re a caregiver, if the cat sleeps in your bed, if you’ve used recreational drugs and a host of other variables.

You might not want to share this data in the first place, but I found that ignoring the journal didn’t affect the core Whoop data, so I didn’t use it much. There’s also a camera option where you can take a photo or selfie overlayed with Whoop data, but it won’t mean much to anyone but other Whoop users and is a half-baked social sharing feature.

Henry Burrell / Foundry

Much more useful is the ability to join or create communities. I joined the Great Britain community and could see I was 2,424th out of about 12,900 users. Tapping into the group showed me that the insane man ranked at number one had recently burned over 3,000 calories in a run and averaged a daily strain of 16.8. To be fair, I felt more compelled to train a little harder and go for an extra run to boost my score and there were more people in the group than I had expected, considering every single person who saw me wearing the Whoop 4.0 asked me what it was.

The app also awards you levels based on how many recoveries you log and simply encourages you not to take off your band. This is all well and good and there are some fine insights, but Whoop doesn’t offer much guidance. There’s a decent volume of data at your hands, but often the advice amounts to ‘you are ready to run’ or ‘get more sleep’ rather than something more sophisticated.

Battery Life & Charging

Whoop 4.0’s battery lasts about three or four days of use. It’s possible not to ever take it off thanks to the included charging accessory, though I have mixed feelings about that.

The small black charger slides onto the band while on your wrist and wirelessly tops up the device as you wear it. But the little charger is only good for one full charge when it itself is fully charged, which you do via USB-C. You won’t want to lose it either, as a is $49/£44/€49.

Henry Burrell / Foundry

It means you have to charge up the charger and then clip it on to charge the Whoop band, which takes about an hour from empty. If you forget to charge up the charger, you’ll end up with a dead Whoop, though the app pings you reminders to charge.

It’s annoying you can’t charge the band directly with USB-C, because if you lose or misplace the charger accessory there is no way to charge it. I understand the charger is small so you can wear it (even if it does look like a parole GPS tracker) but needing to charge it so often when we are used to, say, wireless earbud cases holding a few charge cycles, is annoying.

Price & Availability

The worst thing about Whoop 4.0 is the pricing. Whoop is the name of the service more than the device or its bands, and that’s what you pay for on a subscription basis. Without the subscription, you can’t access your data so it’s essentially a paywall.

The Whoop 4.0 band is free with , which costs $20/£18/€20 per month if you sign up for a 24 month membership ($480/£432/€480 upfront), $25/£22/€25 per month for annual membership ($300/£264/€300 upfront), or a pricier $30/£27/€30 per month with a 12 month minimum.

If you cancel, you must keep paying till the end of the minimum period. There’s no monthly rolling option, which sucks, as similar (but cheaper) service Fitbit Premium does.

Personalised engraving is only available in the US and will cost you an extra $25 (you can see the engraving while wearing the band).

You can also pay an additional $12/£14/€14 per month for , which gets you a complimentary piece of clothing or band every three months, money off all accessories, and other perks.

Henry Burrell / Foundry

Verdict

I’ve already mentioned the insanely expensive bands, and I think they are the thing that most clearly reveals the aspirational, exclusive branding and lifestyle that Whoop appears to rely on for its sales.

Yes, Apple Watch bands cost $49/£49/€49, but for less than the price of a 24 month Whoop subscription you could buy an Apple Watch, which does more, would last longer, and doesn’t require a subscription.

That is a slightly reductive point as the Apple Watch is a very different product from the Whoop 4.0. But it highlights how the Whoop service is for a specific subset of people who want to record cardio strain and their recovery data and don’t mind wearing a band every hour of the day and night.

After three months of me doing exactly this, I can’t help but feel I would rather pay upfront for a product like this and not have a subscription to pay.

Committing to pay so much to try out a relatively basic fitness tracker will put some people off, but if you want a tracker that focuses on cardio data and makes you more mindful about strain and sleep, it’s a good choice. Just don’t lose the charger.