4iiii's Viiiiva external heart rate monitor is the budget fitness tracker you've been looking for

The affordable option.

Viiiiva 4iiii
(Image: © Mike Sawh)

iMore Verdict

The 4iiii Viiiiva is an affordable heart rate monitor that delivers accurate data and offers some useful extras for when you’re not sweating it out with Apple’s fitness app.


  • +

    Lightweight design

  • +

    Accurate heart rate data

  • +

    Nice, durable design


  • -

    Slightly fiddly replacing battery

  • -

    Isn’t the best-looking monitor

You can always trust iMore. Our team of Apple experts have years of experience testing all kinds of tech and gadgets, so you can be sure our recommendations and criticisms are accurate and helpful. Find out more about how we test.

The 4iii Viiiiva is a heart rate monitor from a brand better known for its cycling power meters. That doesn’t mean this is one that can’t live away from your bike with the Bluetooth connectivity on board to let you connect it to an Apple Watch and bring it into the Apple Fitness Plus fray. There’s some connectivity extras here if you want to share data to other fitness equipment and it also offers strong battery life to keep you tracking workouts for some time.

4iiii Viiiiva: Price and availability

Viiiiva 4iiii

(Image credit: Mike Sawh)

The 4iiii Viiiiva has been around since 2012 and is available from 4iiii’s website and from other retailers. It’s priced at $49.99/£49.99 so while not a super cheap monitor, it’s similarly priced to other chest strap-style monitors from the likes of Polar and Wahoo.

4iiii Viiiiva: Specs and features

Viiiiva 4iiii

(Image credit: Mike Sawh)

The Viiiiva uses a pretty typical ECG sensor to track heart rate during exercise and is powered by the kind of lithium coin cell battery that shouldn’t need replacing potentially for over a year depending on how regularly you use it. 

It has an IPX7 waterproof rating, which means you can submerge it in water up to 1 meter for 30 minutes, but it’s really about being durable enough to fend off sweat and rain. There are both Bluetooth and ANT+ connectivity options along with an ANT+ sensor bridge that’s perhaps not going to be massively useful for Fitness Plus but is useful if you’re a Zwift fan as well.

4iiii Viiiiva: Build and Performance

Viiiiva 4iiii

(Image credit: Mike Sawh)

It’s fair to say that the Viiiiva doesn’t feel or like the most high-grade monitor out there, but from a connectivity and performance point of view it ticks the boxes. We successfully paired it with two different Apple Watches without issue and while 4iiii doesn’t do anything particularly to improve the comfort and fit of the strap, we found it fine to use for a range of different workouts. 

While you won’t need to think about replacing the battery for a while, we did find the compartment a touch fiddly to deal with. Ultimately, this is a good-performing monitor that lacks the sleekness of other monitors but delivers where it matters.

4iiii Viiiiva: Competition

Wahoo Tickr X

(Image credit: Mike Sawh)

This monitor definitely sits at the cheaper end of the best heart rate monitors for iPhone and Apple Watch, competing with more established names like Polar and its H9 monitor as well as Wahoo’s Tickr X. Those two monitors have arguably more premium looks, though performance, connectivity, and battery-wise, you can expect much of the same in terms of tracking your heart rate during exercise.

4iiii Viiiiva: Should you buy it?

You should buy it if…

  • You want an affordable heart rate monitor
  • You want good heart rate accuracy across different exercises
  • You don’t want to charge another device

You shouldn’t buy it if…

  • You want the best-looking heart rate monitor
  • You’re looking for the most comfortable heart rate monitor available

4iiii Viiiiva: Verdict

Viiiiva 4iiii

(Image credit: Mike Sawh)

The 4iiii Viiiiva design doesn’t scream high grade, but ultimately it’s a strong performing heart rate monitor that can handle tracking your heart during steady and higher intensity workouts and has the necessary connectivity smarts to work with your Apple Watch. It’s got a good level of durability and while the ANT+ bridge feature isn’t going to be massively useful for most, those who spend plenty of time on their bike paired to other connected gear will. If you’re just looking for a cheap heart rate monitor that’s accurate and easy to use, this is well worth picking up.

Michael Sawh

Michael is a freelance journalist who has covered consumer technology for over a decade and specializes in wearable and fitness tech. Previously editor of Wareable, he also co-ran the features and reviews sections of T3, and has a long list of bylines in the world of consumer tech sites.

With a focus on fitness trackers, headphones, running wearables, phones, and tablet, he has written for numerous publications including Wired UK, GQ, Men's Fitness, BBC Science Focus, Metro and Stuff, and has appeared on the BBC Travel Show. Michael is a keen swimmer, a runner with a number of marathons under his belt, and is also the co-founder of YouTube channel The Run Testers.