Polar Grit X review: This grit is great

The Polar Grit X is a fitness tracker aimed primarily at runners and athletes, with a heavy emphasis on long distance. It is also a very strong option for tracking a wide variety of other activities, and a compelling health tracker for general users. With an appealing design, a huge number of features, (mostly) accurate tracking, and amazing endurance, it has a lot going for it.

However, the Polar Grit X is not is particularly intuitive to use. Nor is it a replacement for a smartwatch. But if you’re okay with those limitations, read our full Polar Grit X review to see if this is the right watch for you.

About this Polar Grit X review: I used the Polar Grit X for around 10 days and tested it over multiple workouts. The Polar Grit X review unit was provided to Android Authority by Polar.

Design and comfort

Close Up Polar Grit X

Credit: Adam Sinicki / Android Authority

I don’t want to spend too much time discussing the build quality and appearance of the Grit X. While this is an upgrade over previous wrist-worn trackers from Polar, it’s still very much a case of function over form. I’ve seen other reviewers describe the build as premium or even luxury. However, coming from an Apple Watch, it feels rather mundane. There are no stand-out design features, and it’s a little on the large size with its 1.2-inch display. Additionally, there’s only one size, which may be a sticking point for those with smaller wrists.

This is a watch for the kind of person that wears their “fitness ethos� on their sleeve (pun intended) and what’s here is perfectly functional. It is a fashion statement in that it lets everyone know that you like to train. Unfortunately, the price tag would be at home on a more premium-feeling product.

It’s durable, too, which is great news if you plan on leaping into rivers and scrambling up rocky paths. That’s thanks to a stainless steel bezel and buttons and its Gorilla Glass 3 display. The watch is MIL-STD-810G rated. Anyone that likes to train rough will appreciate it. This is a very cool feature in itself and it may be a real standout for some. Even if you don’t need military-grade resilience, it’s nice to know it’s there.

Side Buttons Polar Grit X
Polar Grit X Water Resistance
Polar Grit X on Wrist

There are some thoughtful design touches here, as well as a few misses. The buttons are nicely textured, for example (which is an improvement over the Vantage V). This is handy when your fingers are numb with cold or covered by thick gloves. The quick-release watch strap mechanism is also very welcome. Mine came with a practical-looking khaki, but you can swap them out for any standard 22m strap.

On the other hand, I found that the main “select� button was easy to trigger accidentally when bending my hand or slipping on a boxing glove.

The screen doesn’t get the brightest, and the large bezels aren’t that attractive. It can be tricky to see the screen in daylight too, and there are no fancy watch faces. I get that this isn’t meant to be a showy smartwatch, but options from the likes of Garmin fair a little better with aesthetics. Still, that’s subjective and your mileage may vary.

Also read: The best Garmin watches you can buy

I didn’t find the Grit X to be an overly comfortable watch to wear overnight due to the large screen. The strap also needs to be fastened tightly for the heart rate monitor to work. The sensors are raised on a bump that protrudes quite forcefully into your wrist. The result was that I woke in the night multiple times. I had to take it off at one point because my fingers had gone numb.

This may be a personal thing, but it was worse than other sleep tracking devices, and it’s something to keep in mind.

Polar Grit X Running

Credit: Adam Sinicki / Android Authority

Unfortunately, I also found the UI to be rather unintuitive and fiddly. There’s a touchscreen but it’s only used for input under certain circumstances. It isn’t the most responsive either. Otherwise, you use buttons corresponding to the four corners and one more central button. These should have global functions for getting around. Yet, there are weird exceptions and there’s no indication as to what does what.

The Polar Flow app

Polar Flow App

Credit: Adam Sinicki / Android Authority

Navigation doesn’t get much better in the Polar Flow app itself. Here, options are often hidden away in seemingly arbitrary menus. The app isn’t particularly quick to sync with the Polar Grit X either. You have to sit around for a few minutes if you want to add a new sports profile. Today I can’t get my steps to show on the app at all despite having synced multiple times.

The onboarding experience doesn’t help with this. While the watch paired quickly once I’d figured out how to do it, the app was rather unhelpful in getting me there.

There’s a feeling that this watch/app is designed for those already familiar with the Polar ecosystem. That’s fine if you’re already a fan, but a bit of a shame for everyone else. It’s also a shame that there are no social features here.

Data for days

Polar Flow Website 2

Credit: Adam Sinicki / Android Authority

I really can’t complain about the sheer amount of data available through the app, though. You’ll find all sorts of information about every workout here. That includes average pace, power wattage estimate, ascent and descent, fat burn vs carbs, and much more. The same is true for sleep and lots more.

Better yet, the Polar Flow website is where you can see all that information and more in a much more spaced-out setting. Exporting data is easy. That’s a big win for serious athletes (and reviewers). There’s even a desktop app.

In short: the software side of things is powerful but in need of a redesign.

Polar Grit X new features

Polar Workout

Credit: Adam Sinicki / Android Authority

The Polar Grit X only offers iterative improvements over previous Polar watches.

One of these new features is the ability to extend the battery in the settings. You can dim the (already quite dim) screen. You can turn off continuous heart rate tracking or you can reduce the frequency of GPS recording. This all helps the Grit X to keep pace with you on those super-long runs, while still offering useful insights.

Related: The best Polar watches you can buy

Even without changing any settings, the Polar Grit X is already impressive in terms of battery longevity. At this point in the review, I have been wearing it for over a week. During that time, I’ve made use of constant heart rate monitoring, GPS, and more. It’s only just down to 18%. The Polar Grit X boasts over 40 hours of continuous GPS tracking with the standard settings.

Now throw in the power save features and that can be extended to 100 hours of continuous running! This is a fantastic feature for those that need a device that can keep pace on long runs. That kind of endurance is hard to come by. If you’re running longer than that, more power to you.

The heart rate monitoring has also been improved with modified algorithms and hardware. There is also a new magnetic compass and barometric altimeter for hill splits. We’ll get to some other new features later, but these are mostly software-based. Oh, and there’s now weather information on your wrist for the first time — a rather basic feature but welcome nevertheless.

Smartwatch features

Polar Grit X Smartwatch

Credit: Adam Sinicki / Android Authority

The smartwatch features here are extremely limited and once again, a little fiddly.

All you’re really getting is the option to show notifications on your wrist. Phone notifications can be set to either “Off� or “On when not training.� While it’s a small matter, it would be nice to have the option to keep phone notifications on during workouts. I agree that we should avoid distractions during workouts, but that’s not always feasible if you’re a parent who runs two businesses. Sometimes I need to see if the incoming call is urgent. That can happen precisely while running, so it would be useful not to have to pull my phone out my pocket.

While you can set times for a do-not-disturb mode, this isn’t on by default. That’s a sleepless night for anyone who forgets to do this when they first get the watch. Just another small example of the lacking user-friendliness!

Accuracy and data

Polar Grit X Standing

Credit: Adam Sinicki / Android Authority

What you’re really here for is the fitness tracking. Fortunately, that’s precisely where the Polar Grit X excels. You’ll find that this device is very adept when it comes to tracking your runs, cycling, swims, and even weightlifting. Oh, and everything else imaginable too.

That said, the heart rate tracking isn’t the best. The Grit X has a total of 10 lights for heart rate monitoring. These include lights of varying colors which penetrate the skin to different depths and work better with different skin tones. In short, they should work together to provide an accurate reading. In practice, the results are sufficient but fall short of the competition. This is especially true for activities like weight lifting.

See also: Do fitness trackers really work?

I compared results with my Apple Watch and a Polar H10 chest strap across a number of runs, walks, indoor bike rides, and weight training sessions. Chest straps are more accurate, so this is our barometer.

Here is my heart rate during a 7km run, according to the Polar Grit X:

Heart Rate Polar Flow

Credit: Adam Sinicki / Android Authority

If we look at the Polar Grit X (purple) versus the Polar H10 (yellow) during an indoor cycle session, we see that it tracks pretty nicely. The chest strap is definitely more accurate and changes more frequently (as you would expect). However, the wrist-worn Grit X keeps up nicely. This data is definitely accurate enough for most purposes.

Polar Grit X vs Polar H10 Indoor Cycling

Credit: Adam Sinicki / Android Authority

Weight training is notoriously rough on wrist-worn heart rate monitors, however. The act of lifting weights causes the blood vessels to constrict and dilate, altering blood flow. Unfortunately, the Polar Grit X struggles here.

Polar Grit X vs Polar H10 Weightlifting 1

Credit: Adam Sinicki / Android Authority

Weight training is notoriously rough on wrist-worn heart rate monitors.

We shouldn’t mark the Polar Grit X down too much for this — it is to be expected. But surprisingly, this is an area where my Apple Watch 5 actually came out on top. Below is the same workout with the Apple Watch (blue), Grit X the H10 strap.

Weight Lifting Polar Grit h10 Apple Watch

Credit: Adam Sinicki / Android Authority

More importantly though, the Apple Watch was also more accurate during cycling. While all three tracked pretty much identically throughout, the Grit X takes much longer to latch onto the heart rate. See below:

Indoor Cycling Polar Grit h10 Apple Watch

Credit: Adam Sinicki / Android Authority

To be clear: the data provided by the Grit X is serviceable as long as you aren’t lifting weights. It’s comparable to other devices. But given the price, it’s a shame it’s not a top-performer in this regard.

As mentioned though, the amount of data is admirable, and a lot of interesting tips and insights are also revealed through the app. For example, it asks for you to rate the difficulty of the run to get a PRE score (that’s Perceived Rate of Exertion). You also get an idea of your “Cardio Load� and plenty more.

Strength training and other forms of exercise provide similarly detailed breakdowns. However, you won’t find any attempts at exercise detection here. This I’m grateful for. It never works.

Sports profiles

Polar Grit X Design 1

Credit: Adam Sinicki / Android Authority

I wasn’t able to take the Polar Grit X for a swim, but it is water-resistant up to 100m. Reports from other users have been positive in this regard. During said swims, you’ll get information regarding your heart rate, swimming style, distance, strokes, pace, and rest times. It works in open water as well as pools, although there is no readout for water temperature which would have been useful.

The sheer number of different sports profiles available (130+) is extremely impressive. You can add horse riding, orienteering, or Nordic walking to name just a few.

HIIT and guided workouts

Then there are the HIIT sessions and guided workouts. While all these features exist on other fitness trackers, it’s rare to find all this on a single device. This helps the Grit X stand out as one of the most comprehensive offerings on the market right now. It also broadens the potential audience beyond distance runners to include gym bunnies and those serious about their New Year resolutions.

The guided workouts are fun. You’ll receive recommendations based on your workout history thanks to Polar’s FitSpark, which makes its way over from previous Polar devices. These recommendations are also influenced by the nightly recharge score, which makes them more useful and interesting. This is a great example of a company looking at health and fitness in a more holistic manner. Your ability to train is based on numerous factors, and the best fitness trackers should keep that in mind.

Training Load Pro meanwhile shows you how your recent training frequency and intensity compares to previous weeks and months.

The guided workouts are fun.

While all this stuff is good, it can be a little hard to find any of it in the app. Keep in mind you can’t install third-party apps on the Grit X either. This is one way in which other devices can catch up and surpass the Grit X.

No auto-detection

Polar Grit X On Grass

Credit: Adam Sinicki / Android Authority

One thing missing here is the ability to automatically detect workouts — even simple things like walks. While this can be hit and miss on other devices (I’m looking at you Apple), it’s a great feature on others (hello Fitbit). This is a drawback because it means spontaneous walks aren’t recorded on the watch/in the app. If you forget to start a workout before jumping in, it won’t be there either. It will just count steps.

This feature has been around long enough on other devices that it would be fair to expect it on an expensive sports watch. It’s the biggest omission in terms of the fitness-tracking aspects of the Grit X.


GPS is highly accurate, too. Across all my runs, the Grit X matched other methods of GPS tracking. The GPS was also very quick to get a lock. There’s even route planning so you can avoid getting lost.

Below you can see a route I took on the Apple Watch 5 plotted against the Polar Grit X on a 7KM run. The Polar Grit X is in red:

Apple Watch vs Polar Grit X GPS 7KM Run

Credit: Adam Sinicki / Android Authority

Here it is again on a 30-minute walk:

Walk Heart Rate Polar Grit X vs Apple Watch

Credit: Adam Sinicki / Android Authority

As you can see, the two are pretty much identical all the way around with no major differences. And the Apple Watch 5 has great GPS, so it’s a good standard to live up to.

See also: The best GPS running watches you can buy

Health tracking

When you’re not actively training, the Polar Grit X is still a highly useful device thanks to a wide range of powerful health-tracking features.

Sleep tracking

Sleep Data Polar Grit X

Credit: Adam Sinicki / Android Authority

The Polar Grit X also works as a sleep tracker, at least in theory.

As I mentioned, I found the watch to be rather uncomfortable to sleep with, which forced me to loosen it. The watch was still pretty tight and yet it failed on multiple occasions to detect any sleep. This resulted in many nights of sleep being missed. On the occasions it did work, it provided all that usual, useful data. That includes a breakdown of deep/light/REM sleep, along with total sleep time, resting heart rate, and more. If you record a few days of sleep in a row, you’ll get feedback as to how effective your sleep is at boosting recovery.

I don’t want to mark the Polar Grit X down too harshly for its failings here. After all, I’ve read plenty of other reviewers who didn’t experience this. This may be a personal thing, as I’ve had similar issues with some other devices. But it’s certainly worth keeping in mind as some people may have the same experience.

What does stand out as positive though, is the “Nightly Recharge� score. It gives you an idea of your current state of recovery. Even better is the way that it is integrated with other data points to provide useful, actionable advice. You get similar data from Garmin’s Body Battery feature, as well as Whoop’s recovery data.

General health tracking

Polar Grit X Health Tracking

Credit: Adam Sinicki / Android Authority

There are also a number of more general health-related features. “Fuel Wise� will track your water and carb consumption. This is aimed at endurance athletes in particular that are carb-loading or trying to stay hydrated. It’s fairly comprehensive and also includes suggestions to consume carbs during workouts based on estimated calorie burn/primary fuel source.

There’s also a guided-breathing mode called “Serene.� There are comparable features on many trackers. The idea is to provide guided breathing exercises to help you relax. What’s great about this one is that you’ll get real-time biometric feedback showing you how well you’re doing. That’s something I feel has been sorely missing from other similar offerings (like Apple Watch’s default breathing reminders). Anything that gets more people meditating is a win in my book. Like Fuel Wise, this is a far more fully realized version of a feature that appears in a half-hearted fashion on other devices (pun unintended).

The combination of health tracking, suggestions, sleep tracking, meditation, and guided workouts, however, makes for a fairly comprehensive fitness tracking experience. Whereas some fitness devices only really come in handy when you decide to count calories or go on a run, the Grit X can really become an active part of your routine. It genuinely helps motivate you and guide you through workouts. This isn’t something you can say about all similar devices.

Polar Grit X specs

  Polar Grit X
Display 1.2-inch touchscreen, always-on
240 x 240 resolution
Gorilla Glass 3
Build MIL-STD-810G
Stainless steel and glass with reinforced polymer back
Water resistance 100M
Smartwatch features Notifications (including 3rd party apps)
Sensors Heart rate monitor
Ambient light
Connectivity Wi-Fi
Battery 346mAh
7 days with standard use (advertised)
40 hours with continuous GPS use (advertised)

Polar Grit X pricing and availability

The Polar Grit X is available for $429.95 in the US or £379/€329.90 in Europe. It is a more expensive fitness tracker, which is only somewhat reflected in the features and build quality. The Garmin Forerunner 945 is comparable in terms of price and specs. The Garmin model, however, offers support for custom apps and watch faces. It also has a brighter, more responsive screen and offers more smartwatch features. Nevertheless, it “only� offers up to 60 hours in its “UltraTrac� mode. If this is an issue for you, then color me impressed!

Alternatively, the Fenix 6, also from Garmin, is a multisport watch that is every bit as versatile Grit X. You’ll miss out on the extreme battery life but it’s still exceptional and has lots of settings for squeezing out extended GPS runs.

Polar Grit X
This grit is great
The Polar Grit X is a comprehensive and highly accurate fitness tracker, but may not appeal to more casual users.

Those on a tighter budget could opt for the significantly less expensive Polar Vantage M. It comes with many of the same features and up to 30 hours of continuous GPS tracking. Again, that’s more than enough for most humans!

Ultimately, whether or not the Polar Grit X represents good value for money for you will depend on just how much you need that extra endurance and longevity.

Polar Grit X review: Closing comments

It may sound as though the Polar Grit X is a mixed bag. In some ways it is. I’m really not a fan of the UI and don’t particularly love the design. But what really matters on a device like this is the fitness tracking. In that regard, this watch is feature-packed and endurant for long runs. It’s a shame that the heart rate monitoring wasn’t better, however.

If you’re a casual user looking for a smartwatch that’s also a fitness tracker, or if you’re new to the world of fitness tracking and want something easy to get to grips with, this isn’t it.

For serious long-distance athletes, the Grit X is a solid option, if not my first choice. Between its tough design, useful data insights, and wide range of features, this is a serious piece of training kit.

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