Garmin Fenix 6S review

The Garmin Fenix range features nearly 20 versions – and the Fenix 6S is the smallest of the lot.

While a chunky build is synonymous with the Garmin Fenix, the Fenix 6S shrinks everything down into a more wearable package.

It’s certainly the best Garmin Fenix for women and equally ideal for anyone who feels that the larger case size of Fenix watches is too bulky on the wrist.

But is the Fenix 6S still a worthy sports watch and are there any sacrifices made to enable this smaller build? Let’s find out.

• Check out our guide to outdoor watches with navigation
• Find out our top running and multisport watches
• How it compares: Polar Grit X vs Fenix 6

Garmin Fenix 6S key features:

• 1.2-inch
• 42mm case size
• 240 x 240 pixel
• 61g
• Six data fields
• 20mm strap
• 9 days smartwatch
• 25 hours of GPS
• 50 hours Max Battery tracking
• Pulse Ox, altimeter, barometer, compass
• Heart rate, VO2 Max
• TOPO mapping

Fenix 6 models explained

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Left to right: Fenix 6X Pro Solar, Fenix 6S, Fenix 6 Pro

The Garmin Fenix 6 comes in multiple flavors and price points, so we'll just break them down here first.

• Garmin Fenix 6/Pro – The standard 47mm version, adds music, Wi-Fi, maps 
• Garmin Fenix 6S/Pro – A smaller 42mm case with slightly lower battery life, adds music, Wi-Fi, maps
• Garmin Fenix 6X – Bigger screen, slightly better battery, music, Wi-Fi, maps as standard 
• Garmin Fenix 6X Pro Solar – Solar panels for extra battery life, music, Wi-Fi, maps as standard 

Design

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The Fenix 6S comes with a 42mm case size, as opposed to the 47mm of the standard Fenix 6, and 51mm for the Fenix 6X Sapphire.

That’s a massive downsizing in wrist real estate. It’s got a 1.2-inch transflective display with a 240 x 240-pixel resolution. It’s a lower pixel count than the larger watches, but the same general quality.

It’s the same screen found across most Garmin sports watches, and let's make no bones about it, is dull, lifeless and in some lights requires you to manually activate backlighting with the top-left button. However, there is a welcome wrist-raise backlighting.

However, it’s extremely power efficient and always-on and this sacrifice in aesthetics enables some of the Fenix’s best features.

The Fenix 6S weighs 61g with the strap, lighter than a standard Fenix 6 which is 83g. A significant saving.

A nod to its more female-friendly aesthetics, there’s a thin color-coded bezel that offers a bit more class than the standard Fenix. We got a fetching black with a gold version, but there’s also powder grey and gold and straight black. They look great, which is so rare for a sports watch.

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Elsewhere it’s all the same as a standard Fenix. There’s no touchscreen, instead, there’s the five-button array which works just the same as the rest of the Fenix devices. It’s generally pretty easy to use – although the huge array of options and customization the Fenix offers is more often than not hidden behind a very opaque menu system. Garmin knows this, and new users will get irritating “tips” displayed on the watch.

You get a serious amount of sensor tech built into the Fenix 6S, which is a large part of that punchy price tag.

Optical heart rate is a given, but it also features the Pulse Ox sensor, which can track blood oxygen. This comes into its own for sleep data, which will show respiration when you’re in bed. You need to turn this on as it will affect battery life.

There’s an altimeter, barometer, and compass, which will offer elevation and climbing data during a host of activities including skiing, climbing, and hiking.

When ascending this will enable the ClimbPro feature which will show you the details including distance, time, and heart rate. You can also pre-load climbs and ascents to pre-plan them.

Sports tracking

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While the Garmin Fenix 6S has shrunk in size, the amount of sports tracked hasn’t.

And unlike options like the Vivoactive 4 which has a large sports tracking selection, it’s the detail you get and the level of analytics that makes the Fenix 6 the best.

You get running (trail, indoor, outdoor, treadmill), biking (indoor, outdoor, MTB), pool and open swimming, climbing, skiing and snowboarding of all types, triathlon, strength, SUP, rowing, kayaking, golf, hiking, yoga and even more via the Connect IQ platform of apps.


And the analytics is insane. Running offers top-notch dynamics and VO2 Max analysis, including Training Effect, Training Status, HRV, stress, Body Battery, recovery, and even recommendations on the types of workouts missing in your weekly plan.

This is some of our favorite data, and a huge reason to invest in the Fenix 6. As runners, we’re addicted to the Training Effect and Training Status data, which is a great way to evaluate sessions.

The Stress Score and Body Battery have also proved useful in assessing readiness for training – and in some quite hectic periods of training sessions have proved fairly accurate in highlighting fatigue.

You can get equivalent data from the Forerunner 945 - although that’s limited to the key triathlon sports. You will also find many of the VO2 Max and recovery stats on the Forerunner 245 and 645 – but again, not the full gamut.

The VO2 Max data you find on Fenix 6 watches comes from Firstbeat and they’re one of the best in the business in tapping into heart rate variability data and crunching the numbers to analyze recovery and training effects.

Back with the Fenix 3 we put a series of watches up against a laboratory VO2 Max test and found that its data was closest to the lab result.

It’s important to note, however, that VO2 Max and all the lovely data that are produced from it is very much based on running. You won’t get the same insights from hiking, or even busting big functional fitness or CrossFit workouts in the gym. It has to be an outdoor run with GPS, so if you’re not a runner, you’re going to be missing out on a lot of this juicy data.

Fenix 6S running and trekking

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There’s no difference in the running tracking – or any sports for that matter – from the main Fenix 6. It’s one of the best running watches on the market. You can have up to six pages of data to cycle through - all set up from the watch itself.

Data include pace, and distance time information. – but also lap data, cadence, heart rate, zones, and more. It’s a top-running experience, but no different from top-end Forerunners as we’ve already mentioned.

We found GPS accuracy to be top-notch across a range of tests and certified races.

The Fenix 6S also has the PacePro feature found on the other Fenix 6 watches – and now on lower devices like the Forerunner 945 and even 245. This enables you to pace runs based on GPS data you download from the Garmin Connect app, even taking into account split times on hills. It’s not a perfect system – and you can read our full testing separately.

When trekking you also get the TOPO maps and the compass, to help navigate when you're out in the wild. More on those below. You can also swap between power modes mid-hike, so if you're getting low on battery you can put it into the gentler UltraTrac mode.

Fenix 6S mapping

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The Fenix 6S also features the same TOPO mapping – and while it's a nice feature to have, we still have reservations about its usefulness and usability.

In most workouts (running, trekking, etc) you can cycle through the menus to a map screen. You can see what's around you, roads, landmarks, and more. There's also a feature that shows points of interest.

The mapping isn't really at the level of detail you need for proper trekking and shows nothing in the way of contours of the land – or anything short of major trails. A lot of the time you just see yourself in white space – although the compass works to show your heading, which can be useful if you go off-piste.

Landmarks are quite neat, and you can pan/zoom using the buttons, although this is quite a faff the small screen means that by the time you've zoomed out to see something (anything) useful, it's too small to work with.

The feature does get more useful if you add GPX data to follow waypoints on a run or hike, and the extra data from the TOPO helps put your run in context with placements of rivers, woods, and the like. It's not good enough to go navigating your way around the wilderness without a proper map, however.

Fenix 6S heart rate accuracy

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The Fenix 6S uses the same Elevate sensor found on Garmin’s watches – and predictably, came out with the same results.

In short, if you’re a steady runner then you’re likely to be happy with the accuracy of the wrist-based HR. We found good results versus a chest strap across runs of all distances.

However, if you’re into HIIT sessions, you’re going to run into problems.

We were a little surprised by the performance of the Fenix 6S in a track HIIT running session and found the sensor to be well behind the chest strap – coming out with some seriously squiffy data.

And unsurprisingly, the data was almost the same as the Garmin Venu – which uses the same sensor.

As you can see from the data below, the chest strap intervals are fully formed, while many of the latter intervals from the Fenix 6S don't come close to being fully tracked, with heart rate peaks missing the absolute top end, but also recovery not properly tracked between bursts.

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There are a few takeaways here. First is what we always say: optical data is fine if you’re looking for a guide to your performance and your exercise – be it running, cycling, skiing, etc – is generally steady.


If you’re focused on data – or you’re doing HIIT and want accurate HR results – use a chest strap. The Fenix 6S is compatible with ANT+ sensors.

This isn’t a Garmin problem, it’s the same for any optical sensor on the market and it’s not going to change anytime soon.

It’s also interesting that the accuracy of the Garmin Fenix 6S, one of the most expensive sports watches around, is the same as much lower devices in Garmin’s range. Pick up a Forerunner 45 and you won’t get more accurate data.

Fenix 6S battery life

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The Fenix 6S’s reduced case size does lead to one major difference over its bigger brothers – battery life. There is quite a large pay-off in terms of longevity from opting for the 42mm device.

The quoted battery life is 9 days as a smartwatch – with up to 25 hours of GPS tracking. That’s down from 14 days and 36 hours from a 47mm Garmin Fenix 6.

One of the big differences between the Garmin Fenix 6 over the Fenix 5 is power management, and this has been streamlined.

Max Battery mode (the new name for Garmin UltraTrac) ups tracking to 50 hours on the Fenix 6S, but reduces GPS accuracy and should only be used for long hikes or ultra-marathon distances. It will also disable the heart rate monitor.

Jacket mode keeps everything alive but turns off heart rate and is good for winter sports where you might have the watch over the top of your coat. It tends to offer around 10% extra battery life.

You can access these power modes by starting an activity and bringing up the menu by pressing and holding the UP MENU button at 9 o’clock. If you choose Power Mode you can choose Normal, Max Battery, and Jacket Mode – and get an estimate of the GPS time you’ll get within that mode.

If you’re not pushing the limits of endurance then we believe the Fenix 6S more than makes up for the battery life sacrifice with its reduced bulk. It’s much more wearable and will suit more wrists.

Fitness tracking and smartwatch features

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It's probably the most detailed fitness tracking experience out there and more geared to sports lovers than, say, Fitbit or Apple. If you're an active person then step counts might mean very little to you, so it's nice that Garmin's Fenix fitness tracking goes beyond the basics.

The sleep tracking experience is also very detailed and can use the Pulse Ox feature to monitor your breathing, as well as heart rate in deep, light, and REM sleep stages. It's one of the most data-rich sleep-tracking systems we've used – but there's not much analysis or actionable/understandable data.

You've also got Garmin Pay and the Connect IQ store. Apps and watch faces can be found and downloaded from Garmin's Connect IQ store.

You also get call alerts and notifications to the wrist. There's not that much screen space for reading messages but at least you won't miss anything.

However, you don't get granular detail over the apps on your smartphone that are allowed to buzz your Fenix.

You can choose no notifications, all notifications, or just calls and texts. We chose the latter after getting fed up with the watch buzzing away for every email, but WhatsApp doesn't count in this mix, so it's a bit flawed.

Fenix 6S vs 6S Pro

There are some extra features of the Fenix 6S that you’ll only unlock if you opt for the Fenix 6S Pro version.

The main one is music playback. You get room for a whopping 2000 songs, including support for offline synced Spotify playlists (if you have a Premium account). Deezer and iHeartRadio are also supported.

It’s not the most user-friendly setup - but fairly easy to use and navigate, and good if you want to leave your phone at home. GPS and music battery life sits at 6 hours - which is fairly short.