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Polar Grit X GPS Watch Review – GadFit Singapore

May 16, 2020

The Polar Grit X ($689 SGD/ $429.95 USD) signals Polar’s intentions to reach out to the outdoor trail and ultra-trail running crowd while maintaining a foothold in the multi-sport domain. The Grit X is marketed as a rugged yet feature-full wearable that will take care of your hill intervals and training load monitoring right down to the fuel intake during your runs.

polar grit x lifestyle 1

I had the good fortune of owning the Polar Grit X at a discount from Polar Singapore in exchange for an objective review.  After 3 weeks of usage and 100 km later, with plenty of it on the hills in urban Singapore, here’s what I have to say.

Polar’s Grit X is the most polished wearable to come from Polar in a long while. While the Vantage line took close to a full year to reach maturity, the Grit X is starting with Vantage’s final state from the get-go. And more.

Save for the absence of Recovery Pro, the Polar Grit X has all the features of the top end Vantage V, and boasts novel features such as hill splitter, Fuelwise, and Komoot compatibility which outdoor and trail users may find useful. But, the goodies doesn’t stop there.

The Grit X has also passed several MIL-STD-810G tests and is certified WR100. Furthermore, this is a full-fledged multi-sport watch with a listed 40 hours battery life.

This is Polar’s rendition of excitement on a wrist. Read on for the detailed review.


In my opinion, the Grit X is the best looking wearable to come out from Polar to date. The watch encapsulates the rugged and outdoors feel without going down the G-shocky route.  

grit x in box

The mildly elevated brushed stainless-steel case cradles the display, protecting it from side knocks and whatever outdoor adventures may bring.

polar grit x picture 1

Notches are cut into the bezel at the 3, 6, 9, and 12 o’clock positions, assumingly for aesthetic purposes. “GRIT X” is boldly embossed unto the side of the watch.

5 buttons together with a touch display control the full workings of this watch. The texturized metal buttons have a robust bounce-back feel further accentuated by the vibration motor. A single red dot suggestively marks the center right button, presumably to imply “press for action.”

polar grit x lifestyle

The touch display, measuring 1.2 inches with 240×240 resolution, views crisply under bright afternoon sun.

polar grit x display under sun

The back-light, activated by wrist flick or button press, appears to be a repeat of the Vantage V situation; a tad dim for viewing. I had to regularly bring up maximum brightness by pressing the top left button. Backlight brightness is currently non-adjustable.

The back of the Grit X resides Polar’s Precision Prime optical heart rate (HR) sensors. This is Polar’s first attempt at unleashing the orange LEDs since these were noticeably absent from Vantage V.

polar grit x precision prime sensors

One big change here is that Polar no longer require pin detection to assess if the watch is being worn. The solution now is based on the single green LED in the middle of the watch. So, light reflection from fingertip or some other surface could cause the device measure something even when the watch is not worn.  

The silicon strap is industry standard 22mm and can be easily swapped out. Unfortunately you only get two watches faces to choose from – Analog or digital. Polar could’ve done better here.

The charging cradle is identical to the one on the Vantage models.

polar grit x lifestyle 3

At 64 grams, the Grit X ranks amongst the lighter premium multi-spot watches out there. For comparison, the Garmin Fenix 6 weighs in at 83 grams while the Suunto 9 is 81 grams.


Polar claims that the Grit X can last up to 40 hours on a single charge with wrist HR enabled along with 1-sec GPS recording intervals. Here’s my experience:

  • 1 hour run with wrist HR and 1 sec GPS+QZSS recording, screen enabled: 2%-3% battery usage observed
  • 2 hours run with wrist HR and 1 sec GPS+QZSS recording, screen enabled: 7% battery usage observed

If I loosely extrapolate, maximum battery life could be anywhere from 24-40 hours.

I thought you should take note that battery depletion rate seemed to differ based on the different reviews I have read, mostly in different countries. I’m unsure if climate could be a factor.

But, I can further add is that there are measures which the user can tweak to reduce battery usage for those long days of usage. For example, GPS recording can be set to every sec, every min, every 2 mins. Wrist HR can also be turned off. And there is a further option to enable a screensaver.

For daily use, the watch easily lasted up to 5 days on a single charge.


To assess the accuracy of the Polar Grit X’s wrist HR, I compared it versus the heart rate recorded by a Polar H10 chest strap HR monitor over a variety of activities which most runners would likely do. Specifically, strength training (either body-weight or free weights), intervals, long runs.

The HR graph recorded by both devices would then be plotted on the same graph and compared visually.

For the bodyweight segment, this was a home workout which included exercises such as incline plyometric push ups, kettlebell deadlifts, floor press, wall marching, goblet split squat, planks. Followed by 4 cycles of speed squats, squat jumps and squat iso holds with rest – essentially a full body workout.

Wrist optical HR sensors don’t usually perform well for strength training. But, in this case, I thought the Polar Grit X performed exceedingly well.

polar grit x heart rate 1

The Grit X took a while to “warm up” and once it did, it largely trended the chest strap HR monitor.

Next we have the outdoor slow long run. Other than the rare spike and dip, the Grit X’s HR recording was as expected.

polar grit x heart rate 2

Finally, we have the hill intervals where, hopefully, the quick increase and decrease in heart rate from the ascent and descent may reveal the weaknesses of the Precision Prime sensors.

polar grit x heart rate 3

Again, nothing too concerning based on my usage. It appears the Polar Grit X was tough enough to fend off anything I could throw at it.

I made this observation because I had a different experience with the Vantage V; that watch struggled at the high HR ranges during hill intervals.

The Grit X has one of the best optical HR performances I have seen in Polar’s wearables to date.

I will add a swim comparison when it is possible.

The bulk of the Grit X’s features hinges solely on the performance of the Precision Prime sensors.

This would include normal training, Training Load Pro, Nightly Recharge, FitSpark, VO2 max estimation from the wrist, Running Index, Serene Breathing and so on.

If Polar’s wrist HR solution works well for you, then the metrics should make good sense. However, if it doesn’t, then you are out of luck. So, check out more reviews before you pull the trigger.


To assess the accuracy of the Polar Grit X’s GPS in urban Singapore, I compared it versus the Suunto 5; the wearable with the protruding antenna that has given me the most consistent GPS tracked routes to date.

The Polar Grit X would be worn on the left wrist while the Suunto 5 would be carried in the left hand with the antenna fully exposed.

Most Singaporeans stay in HDB flats (Housing development board) and we have limited access to vast open spaces for running. Most of us run repeated loops around where we reside so I’ll be doing the same for the GPS comparison as well – running repeated loops.

This loop I run at is flanked on both sides by tall buildings easily 10 storeys high as shown below. The run path is white in colour and superimposed on the 3D map.

For this comparison, I’d be running 12 laps around a roughly 627m loop as estimated from Google Maps. The completed distance should be about 7.5km.

Both the Polar Grit X and the Suunto 5 were put on GPS + QZSS, a combination I found garnered me the most accurate recording in Singapore.  The Suunto 5 was further connected to a Stryd foot pod and the recorded routes are shown below along with the actual route for comparison.

The Grit X recorded a tighter route compared to the Suunto 5, which was a bit wonky in this session.

The plotted distance per loop on Google Maps was about 627m so the total distance should be about 7.5km for 12 loops.

  • The Suunto 5 + Stryd combo recorded roughly 617m per loop or 7.4 km for 12 loops.
  • Polar’s Grit X recorded 680m per loop or 8.19km for 12 loops.

That might set some alarms off but to provide the context, when not paired to a Stryd, the Suunto 5 also recorded roughly 670m – 680m per loop consistently, repeatedly, on previous runs I recorded.

So the recorded distance of the Grit X is actually comparable to that recorded by a Suunto 5 in the absence of a Stryd foot pod.

Here’s another area I run at which might better show why runners in Singapore may face a different type of challenge compared to runners in other countries when using GPS watches – the abundance of tall buildings.

Notice how the GPS route is nicely tight at the bottom left of the picture where there are no buildings and how it looks really jiggle and messy at the top right hand corner where tall buildings are. I thought it’s important to show the challenging conditions.

I have since clocked more than 10 runs exceeding 100 km and the GPS performance of the Grit X has been consistent and stable. There were the occasional wonky sessions such as a single lap being off as shown below but by and large, the Polar Grit X did pretty well in Singapore’s concrete jungle.

The comparisons I made apply to the watch that I’m using and you may have a different result. I’d strongly urge you to check out reviews by other reputable websites to see how they found the GPS performance of the Grit X.


In Singapore, we lack mountains and high hills; the tallest hill we have is Bukit Timah hill at 163.63m. However, we have a lot of decent slopes where many a runner have done their hill workouts, myself included. So, this new feature is a boon for local runners.

polar grit x hill splitter

What Polar’s Hillsplitter does is that it automatically tracks your uphills and downhills in real time if certain conditions are met. To see this reading in real time, simply scroll to the hill splitter display in the recording mode.

grit x hill splitter on app

You can see from the screen grab above that the watch accurately captured all the uphill and downhill points. The recorded elevation appears to be consistent.

According to Polar Singapore, for Hill Splitter to record a “hill”, the elevation has to be 15 meters for cycling, mountain biking, cross-country skiing, and running profiles (includes trail running), and 10m for walking. Furthermore, GPS recording must be in “1 second” mode otherwise hill splitter would not kick in.

I should also add that, based on personal experience, a certain level of gradient is required for hill splitter to recognise it as a proper “hill.”


This is a new feature from Polar which factors in fuel needs in terms of carbohydrates during any workout.

There are two modes – Smart and Manual.

In smart mode, the watch will ask the user for the intended duration and intensity of your workout along with the planned carbs intake. All three variables can be adjusted. Once that is set, this Fuelwise plan will kick in during your workout to remind you to consume carbs based on user energy consumption determined on HR readings

In manual mode, you set the time interval to consume the carbs. Think of this as a timer that goes off regularly so you can focus on your lengthy workouts.

grit x fuelwise

There is also a hydration intake reminder as well. This is simply a timer that goes off at every fixed interval during the workout. When the time came, the Grit X watch would buzz and the hydration logo would appear on the watch.

Garmin has a similar hydration widget which tracks total hydration for the day, plus another within the mobile app which estimates sweat loss for the workout.

Fuelwise cannot be activated within a training profile. You have to scroll to Fuelwise and tweak all the settings before activating it to be used on any training profile. The only exception is within FitSpark where Fuelwise features are automatically included for long workout sessions.

If you refer to the picture below, you can see from the tiny square of grey icon that I have activated a training target together with Fuelwise to be used for a running workout.

fuelwise for running

The ratio of energy utilized for a particular workout is also provided in app. Whether this is useful or just plain motivational depends on what Polar has in store. As of now, it appears to be a show-and-tell and nothing more.

energy used in polar flow

Even though wearables such as the Grit X can provide reminders for fuel intake, our bodies are unique so the only way to find out what works is to try your own fueling and hydration strategy.


This is the portion I found limiting for usage locally as Komoot does not offer free region access for Singapore. You will have to cough up $45 if you wish to access this feature. Thankfully this is once off.

komoot press pic

From what I found out, this feature offers Komoot-powered navigation with breadcrumb trail directly on the watch.


The Polar Grit X does a good job at all day activity tracking. You get information about your step count, calories burned, active time, distance and even inactivity stamps.

inactivity alert polar

If a buzz comes up on the watch, it’ll be logged in under activities display. With the inclusion of the highest and lowest recorded HR in a day, Polar’s recipe for all day tracking serves to provides an adequate overview of how the day went.

polar grit x all day

There’s also sleep tracking as well but since that is combined with nightly recharge, I will elaborate on that under Physiological measurements.


Unlike most of the other wearable companies which license physiological measurement tools from Firstbeat,  Polar produces their own physiological measurements based on their years of research and data.

There are 4 key training-related features which are dependent on the input from the Precision Prime fusion sensors. They are Running Index, VO2 max estimation from the wrist, Training Load Pro, Nightly Recharge.

Running Index

Running index depends on your heart rate and speed data measured during a run. The run needs to be longer than 12 minutes, with heart rate recordings enabled, together with a minimum speed above 6 km/h / 3.7 mph.

Because of the dependence on heart rate, running in warmer and more humid weather should mathematically get you a lower number given the same speed. According to Polar ” Variation on a day-to-day basis can be affected by all factors that have an effect on the relationship between heart rate and running speed. These factors can be environmental factors such as heat, altitude, air resistance, terrain, and running surface; external factors such as clothing, shoes, calibration of a stride sensor; and internal factors such as training status, mood or dehydration. “

So, if you really want to see your best running index scores, flat ground or standard tracks in cool weather should be the way. Otherwise, be ready for fluctuations depending on where, when, and how you run. As shown by my own running index scores.

To get an accurate reading, you will need to key in your max HR and resting HR.

VO2 max estimation from the wrist

This was previously a feature available only with a chest strap HR monitor but has gradually been rolled out to Polar’s stable of optical HR sensor wearables.

VO2 max estimation from wrist

You strap on the watch snugly, lie down for about 3 minutes and you get an estimate of your VO2 max. This score is dependent on what you indicate as your training background.

So, how do you reconcile the both Running Index and VO2 max estimation from he wrist then? Polar Singapore rep gave me the following response:

The Running Index measures the VO2max from the relation of running speed and heart rate. There can be a lot of variables that affect the results. These factors can be environmental factors such as heat, altitude, air resistance, terrain, and running surface; external factors such as clothing, shoes, calibration of a stride sensor; and internal factors such as training status, mood or dehydration.
The Fitness test is based purely on your heart rate and physical settings. The conditions should always be similar so the test results are as accurate as possible. There are not so many variables in the Fitness test. 

Training Load Pro

The Training Load Pro is a tripartite of 3 unique measurements of your workouts – cardio load, muscle load, perceived load. And this reading is easily accessible from the Polar Flow app after every workout.

Cardio load is how hard the heart works during any workout based on training impulse calculation (TRIMP). So, you will get a cardio load score for all workouts as long as heart rate recording is enabled. 

This cardio load status on the watch display below is essentially your body’s ability to tolerate strain based on the last 28 days over the load it has been receiving for the last 7 days. Cardio load status is the single reading from the Training Load Pro to get a dedicated display on the watch. There isn’t a muscle load or perceived load display.

grit x cardio load pro

Muscle load only appears when measurement of power is involved. And you will get that from a run because the Grit X measures running power from the wrist. However, you won’t see muscle load when you do strength workouts because there aren’t any power measurements involved.

Perceived load is basically your rate of perceived exertion for a workout (RPE).

training load pro

The key thing to remember is that all 3 measurements are adaptive over a period of 90 days. So, the more you use the wearable, the more accurately it becomes at estimating your strain and load.

In order to utilize this training load pro system fully, you will need to spend time to review the stats over time. Otherwise, the numbers will make little sense besides taking up space on the display and in the app.

There is no harm is deferring to the wearable for training feedback but it is necessary to back it up with common sense why certain trends are as such. 

Nightly Recharge

Grit X’s Polar Nightly Recharge is a recovery indicator that shows how well you have recovered from the day’s demands. This indicator combines readings from two aspects – sleep charge and ANS charge.

Sleep charge takes into account details like sleep duration, solidity, regeneration.

ANS charge takes into account heart rate, heart rate variability (HRV) and breathing rate.

The combination of these two measurements culminates in a Nightly Recharge result conveniently viewable on the watch.

There are 6 Nightly recharge outcomes – very poor – poor – compromised – OK – good – very good. You will also receive exercise tips within the Polar Flow app based the Nightly Recharge result and the Cardio Load status.

I compared the Lowest recorded resting heart rate captured by the Grit X during sleep to that of an Oura Ring. Here are 13 days of data. The Grit X was worn snugly. Looks pretty good.

However, I am unable to properly compare the HRV and respiratory rate as both companies have different ways of calculating the average.

I lack the expertise and the information to make accurate assessments when it comes to sleep quality tracking. I see such readings as a rough guide, coupled with common sense that this wearable is unlikely to mirror the accuracy of a full-fledged polysomnography.

That being said, what I found most useful about Nightly recharge is that it benchmarks the current day’s results versus your usual levels from the last 28 days. In that way, it becomes easy to notice anomalies due to short term disruptions in your life.


Review of the day or detailed specs regarding a training session can be done through multiple means. You can access the tracked stats directly from the watch.

Or you can do it on the Polar Flow mobile app, available on both iOS and Google Play platforms.

Polar also maintains a Polar Flow web platform – a more powerful expansion of the Polar Flow mobile app.

It is also on the Polar Flow app and web platform that you can further tweak the Grit X watch’s workout display. The user can customise up to 8 different displays with 4 stats per display.


The Grit X has other useful traning features such as Strava segment, race pace, interval timer, back to start, smart notifications and so on. I won’t be going into the details in this section but will generally touch briefly on what else there are.

The Grit X can connect to compatible training accessories such as external heart rate monitors, foot pods, cadence sensors and so on via Bluetooth Low Energy. However, it is not ANT+ compatible.

Grit X also has native running power readings directly from the device. Interestingly, I found the readings more variable than a both the Garmin running dynamics and Stryd foot pods. And on occasions, susceptible to sudden changes in weather as well.

There is also FitSpark, an on-device guide that suggests daily workouts based on your recovery, fitness level and training history. This can be useful if you are have no idea what type of training you should be doing.A tiny stick figurine demonstrating what the exercises should look like.

Serene breathing is a guided breathing counter which was first introduced with the Polar Ignite but has since been adopted by the Vantage line and the Grit X as well. You set the timer of the exercise along with the duration of breathing in and out and let the watch guide you with soft vibrations.

serene breathing gif

Weather can now be glanced directly from the Grit X as it pulls the data directly from OpenWeather. To get more timely updates, refresh the data by syncing the Grit X to a connected mobile device.

weather on polar grit x


The best thing about the Polar Grit X is that it is shipping as a matured wearable and avoided the fate of its predecessors. I had great fun using this wearable and it definitely sparked joy! In my opinion, the Grit X is a complete solution for training purposes, and it doesn’t matter whether you trail run or not.

Specifically, the Hill Splitter, lengthy battery life, GPS performance, wrist HR accuracy, coupled with the toughness and look of the watch were aspects that were appealing.

Of course, I would like to see what else Polar has in store to further improve this watch via upgrades.

*Update 2nd November 2020. Polar’s new flagship Vantage V2 has some new test features which are apparently not coming to the Grit X. It is a real pity considering the Grit X is less than a year old.

Thanks for reading and I hope you enjoyed the review. You can purchase the Polar Grit X from Polar Singapore or from Amazon where there’s usually a small discount, great return policy, and free delivery depending on where you reside. In return your purchase helps to offset the costs associated with the running of this site. Take care and train hard!


  • Reply Torbjørn May 16, 2020 at 1:48 pm

    Great review!
    One of the better 😀

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