Fitness Gear

Face-Off: Apple Watch Series 4 vs Garmin Forerunner 645

apple watch series 4 vs garmin
Written by Charlie

The Apple Watch Series 4 and the Garmin Foreruner 645 are both popular options for running watches. Which one is best for you? Check out this in-depth comparison to see how both stack up against each in real-world scenarions.

We have made it – we are finally at a point where one of the best (if not THE best) athletic GPS makers in the world has met the biggest smartwatch maker in the world and they go up against each other in much more than just GPS tracking. If you are stuck deciding with the Apple Watch Series 4 vs Garmin Foreunner 645, hopefully this post will help you make this difficult decision! This is the result of almost 2 months of use with both watches (my earlier impressions of the Apple Watch Series 4 were very positive).

Read: How the Apple Watch Series 4 and Garmin Forerunner 645 Stack Up

Comparing the Apple Watch Series 4 vs Garmin Forerunner 645

Price and Deals

These watches are ideal to compare against each other because they have many similar features and even similar price points. The Apple Watch Series 4 is available at two prices, depending on the display size. The 40mm is $399 and the 44mm is $429. On the Garmin side, there are also two versions. The Garmin Forerunner 645 is $399 and the Garmin Forerunner 645 Music is $449.

As far as deals, there have already been a couple of retailer-driven deals on the Forerunner 645. In fact, I was able to get mine for $350 (the music model), and that was before the reward points I applied with that retailer (something Apple does not offer but other retailers have).

For the Apple Watch Series 4, it is still too new. You cannot even earn shopping portal bonuses on purchases of this watch through Apple quite yet. But, you can always watch for the great 15% and 20% discount codes for eBay’s site wide deals to save on it.

Feel and Comfort

Apple Watch Series 4 vs garmin Forerunner 645

They are fairly similar in weight with the Garmin Forerunner 645 feeling a little bit lighter – but it actually is heavier than the Apple Watch! This is due to the plastic body vs the aluminum of the Apple Watch. That is not to say that the Apple Watch feels heavy! If you are coming from a watch like Garmin’s own Fenix series, you will be amazed at how light either watch is.

The Apple Watch Series 4 has a slightly thinner bump on the back of the watch so it does not sit as high as previous models. At the same time, the Garmin Forerunner 645 sits almost completely flat. It will certainly come down to preference and this is likely one of the only areas that the different shapes of the screen may come into play – do you like the fit/feel/look of a square display or a round display?

Personally, I give this category a slight edge to the Garmin Forerunner 645. Again, they are quite similar but the Garmin just wears a little bit more comfortable. With either watch, you can get substitute bands.

Apple Watch Series 4 vs garmin Forerunner 645

The displays are both helpful, but the beautiful display of the Apple Watch Series 4 is certainly a better look

There is no question about it – the Apple Watch Series 4’s OLED display is just fantastic. Apple really used this version to highlight the real estate of potential for their displays with the increase of usable display and you can definitely tell. In fact, all you need to do is to use an app that has not yet been updated to take advantage of the extra screen size and you will be surprised at how much more cramped the previous screens tend to look in comparison.

The new Apple Watch Series 4 not only has more usable display area but also has a gentle rolloff of the display so it is no longer boxy corners. The added display size also helps to fit more information and larger fonts on the display and it is a job well done.

On the other hand, Garmin has stayed with their battery-conserving displays and there are some great advantages to this. For one, the screen is always on. It is also not always bright. This means you can simply take a glance at it during a meeting or whenever you need to without the brightness of the watch alerting your companion that you are checking the time. 🙂 The display size of the round Garmin Forerunner is great for large fonts and clear watch faces as well and it is definitely easy to use for an everyday watch and for running.

Finally, the Garmin Forerunner 645 display allows the battery life on the watch to be stellar, giving you about a week of regular, watch-like use.

For the sheer appearance, this category goes to the Apple Watch Series 4. If you want the better display, the Apple Watch has it. For something always on, go with Garmin. Here is a little Apple tip, though – if you want to just glance at your Apple Watch without the screen coming full-on, just slowly turn the dial to slightly bring up the brightness.


Apple has made great strides in the battery department, while continuing to maintain their “18 hours” of battery life. In truth, it is actually much better than that. But, it will really depend on your use. If you are on it all day, scrolling through stuff, it will kill the battery faster. But, if you are using it to check notifications, interact with your phone on occasion, play music, use maps, go for run, you will find that you will get at least 24 hours and likely closer to almost 2 full days! I routinely get almost 2 days of battery life and that is with an average of a 1 hour run each of those 2 days.

Apple does claim that the Apple Watch Series 4 will give you 6 hours of GPS workout. I have not gone a solid 6 hours in a row yet, but I can tell you I completely believe that, based on the multiplying of my long runs that I have already done with it. I have run 3.5 hours over 2 days and the watch lasted about 36 hours. Not bad!

However, the Garmin’s more conservative display really pays you back in this department! As I said above, you will be getting almost a week out of it as a watch and at least 12 hours of GPS use. If you choose to play music from it while using the GPS, that time will drop dramatically to less than 6 hours. On the Apple Watch side, I actually did not notice much of an increased hit to battery life at all when using music during a workout.

As good as the Apple Watch Series 4 is in the battery department (and it is the best yet and will definitely help 99% of runners accomplish a marathon with it), the Garmin Forerunner 645 steals the show with battery life.

Digital Wallet

Not a whole lot to say on this point – Garmin Pay is picking up some steam, slowly. It only recently this year allowed Chase cards to be added. It can certainly be useful but it does not have the wide market adoption of the Apple Pay system. I’m glad that Garmin has added Garmin Pay to their watches but the Apple Watch is the king in the digital wallet area.

Smart Notifications/Functions

The Apple Watch is built as a smartwatch first with great fitness components. On the other hand, the Garmin watches were built as GPS devices first and have slowly added more of the smartwatch capabilities to their lineup.

That is far from a slam against Garmin. I think they have done a great job with this slower buildup and I am glad they are adding things that are helpful and work instead of just making it a smartwatch with a Garmin app (though I would love a Garmin app on the Apple Watch!).

The Garmin Forerunner 645 does a great job with smart notifications. Basically, whatever apps you have allowed to give you notifications will likewise notify you on the Garmin. You can choose to have it as an audible notification and/or a vibration notification. They also work during workouts. Garmin also has a limited app database, but it is quite limited.

The Apple Watch Series 4, of course, handles notifications very well. While Garmin has given their displays a splash of color, nothing replaces getting the full color notifications from apps on your Apple Watch. I love getting my Twitter feed updates with the photos or iMessages coming through with the photos on the Apple Watch (that does not happen on the Garmin).

The Apple Watch Series 4 wins this category handily with tons of apps and notifications.

GPS Accuracy

Ok, you are buying one of these watches for its ability to track your workouts, probably running. How well does each do that? The truth is that Garmin has always been pretty good at this, though there are some anomalies at times. You will find people on the Garmin boards complaining about GPS accuracy on various models so they don’t have it perfect but it is very good.

Apple Watch Series 4 vs garmin forerunner 645

This is the GPS map from the Garmin Forerunner 645. You can almost see where I was bouncing around a bit – and it is a little jagged with that.

Apple has definitely improved their GPS capabilities on the Apple Watch Series 4. I have found it to be pretty good at tracking with one big, glaring issue. Apple, obviously, likes things to look nice and they like their curves and round edges. They take that affection of those to their smoothing of GPS tracking as well. If you look at a GPS map of an Apple Watch run, you will find it to be more smooth in the lines than other watches. While that by itself isn’t a huge problem (because it still gives roughly the same information as the Garmin), how Apple starts tracking is a problem for me.

Apple Watch Series 4 vs Garmin Forerunner 645

This is the Apple Watch GPS map. You can compare it to the above Garmin one and notice the smoothing that Apple does vs the more jagged tracking on some parts from the Garmin

Anyone that has run with a Garmin knows that you step outside, select the run option and then wait while it acquires the GPS signal. You will see it flirt a bit with the green-to-go part sometimes but, with each new model, the wait time is less and less. Basically, you could wait to tie your shoes until you are outside and waiting for the GPS and it will probably be done before you are tied up.

Not so with Apple! They actually don’t have some magic GPS radio that has it ready to go on a split second notice. You may think that if hit the Apple Workout app and select to start. You get the 3-2-1 countdown and it starts. But, it does acquire the GPS signal that fast. Instead, for about the first 1/10 mile or so, it uses that time to acquire the signal so you will not see any accurate pace information for that first portion.

Apple Watch Series 4 vs garmin Forerunner 645

Apple uses a 3 second countdown that really doesn’t have anything to do with GPS acquisition

It does catch up and pretty quick but it is something to be aware of.

Having used both the Garmin Forerunner 645 and the Apple Watch Series 4 during the same workouts for 6 weeks now, both are really good but on known distances, I found the Garmin Forerunner 645 to be just a little more accurate.

Heart Rate Monitoring

This is another area where the Apple Watch Series 4 has improved. Again, it will do the same thing as the GPS acquisition for the first part of a run but, overall, it is more accurate than before. Neither watch will be as accurate as a chest-mounted heart rate monitor but they are very good.

Apple Watch Series 4 vs garmin Forerunner 645

Apple’s heart rate chart shows pretty accurate tracking

One of the dings with the Apple Watch in the past was that it did not react fast enough for people doing heart rate training with speedwork. I don’t do my runs by heart rate but I did notice it responded fairly quickly (I keep my Garmin on heart rate average for the mile).

Apple Watch Series 4 vs garmin Forerunner 645

The Garmin’s heart rate chart is also very good and pretty accurate

Both the Garmin Forerunner 645 and the Apple Watch were very similar with their monitoring but I found that the Apple Watch Series 4 responded a bit quicker and with more accuracy (when compared to a chest strap) than the Garmin – but just by a bit.

Smartphone Interaction

This is another easy category – Garmin has limited interaction (you can answer a phone call, but not talk through the watch, for example) with you’re smartphone. The Apple Watch Series 4 has seamless integration and interaction with the iPhone, and so it should. Without a doubt, the Apple Watch Series 4 is the better watch for smartphone interaction.


Both the Apple Watch Series 4 and the Garmin Forerunner 645 Music have the ability to load music on the device (and now, both work with Spotify as well!). Surprisingly, I was able to load music faster on to my Garmin than the Apple Watch. I found the process for loading music to the Apple Watch to not be, well, very Apple-like. To load it, you must have it on the charger. Ok, I understand the Garmin needs to be plugged in to the computer to load music, but with the seamless integration between the Apple Watch and the iPhone, why can I not just transfer my music from the phone to the watch when it is on my wrist?

As far as using music from either device, both work well but I give the edge to the Apple Watch because this is where the touchscreen can really come in handy. Also, I found the bluetooth connection between the watches and my various earbuds to be stronger with the Apple Watch over the Garmin.

In the music category, the Apple Watch Series 4 showed itself to be stronger.

Using on the Run – Running Apps and Interaction

Ok, let’s get down to the actual run! If you want a device that delivers good, quality data for you to observe during and after a run and if you want it to be no-mess, the Garmin Forerunner 645 is for you. You can setup the display to show up to 4 fields of data and the kinds of data you can have in those fields is pretty limitless in the scope of your activity. These displays allow you to customize the face of the watch for your workout to give you the information you need or want and you are not stuck with a software manufacturer’s decision for you.

The Apple Watch Series 4 (my first race with the Apple Watch Series 4), on the other, is kind of like being able to keep your life on your wrist while you workout. Whether or not you think that is a bad thing is up to you! I found it helpful to get full display notifications (the Garmin appears just at the top and you need to click a button to view it) without having to do anything. It enabled me to tell right away if a text message needed an immediate response or if I could just handle it later.

Customization in Apps

However, the Apple Watch Series 4, for all of the available running apps, really does not come close to the level of customization with data that the Garmin has. I used a number of apps and found different issues with all of them for the kinds of data I wanted on my wrist. If you want a ton of data, WorkOutDoors can give that to you but I really did not like the interface. The Apple Watch Workout app now gives you Pace Alerts and Rolling Mile, both of which can be useful. Another app I liked for giving actual average mile pace numbers was iSmoothRun. If you want to have your runs seamlessly uploaded to Stravayou will need to use that app unless you want a third-party app to do the upload for you.

Yet, none of those did a good job when it came time to do speed workouts. The Garmin is great since I can setup a workout ahead of time or view the metric I need to track easily. The Apple Watch does not give that to me.

At the same time, it is very easy to flip between various apps, including the music app, on the Apple Watch. For the Garmin, that takes a little more work but I could flip around easily through a music library on the run with the Apple Watch – something I cannot do with the Garmin. I could also do something like make a call quickly and easily while running and without touching my phone – again, this was something I cannot do with the Garmin.

Method of Interaction

Finally, one more big area of distinction is the method of interaction. The Apple Watch uses a touchscreen with the digital crown and side button. The Garmin Forerunner 645 uses 4 buttons and has no touchscreen. Personally, I prefer the button method over the touchscreen since, even with the larger display of the 44mm, it can still be quite easy to touch the wrong option when you are pausing a run or something similar (and instead end it, something that can be very disappointing!).

This is a tough one – it will really come down to what you want to get out of your watch when you run. If you are more of a purist/data-seeker, the Garmin Forerunner 645 cannot be beat. If you don’t mind the shortcomings of the apps for the Apple Watch (which could be easily updated with a software update, which is why I am so frustrated with Apple for not giving a more robust app), the Apple Watch allows you to continue with your regular life while on the run and you don’t even have to break stride to take care of various tasks.


SpecificationApple Watch Series 4Garmin Forerunner 645 Music
Battery LifeGeneral Use: 18 Hours
GPS Use: 6 Hours
GPS w/Music: 5 Hours?
General Use: Up to 7 Days
GPS Use: Up to 14 Hours
GPS w/ Music: Up to 5 Hours
Music Storage16GB of storage3.5GB of storage
Water ResistantUp to 50 MetersUp to 50 Meters
Native Sleep TrackingNoYes
Built-in Heart Rate MonitorYesYes
Always-On DisplayNoYes
Multi-Sport CapabilityYesYes
Glass materialIon-X Strengthened GlassChemically Strengthened Glass
Weight36.7 Grams42.2 Grams
Dimensions44 x 38 x 10.7 mm42.5 x 42.5 x 13.5 mm
SensorsOptical heart sensor, electronic heart sensor, gyroscope, barometric altimeter, accelerometerOptical heart sensor, barometric altimeter, compass, gyroscope, accelerometer, thermometer
Compatible with iOS and AndroidNoYes
Switchable watch bandsYesYes (20mm bands)

So, which is better? For the first time ever, I am really leaning more towards the Apple Watch (even though I still wear my Garmin as well for speed workouts and races). I think Apple has done a much better job with the Apple Watch Series 4 and I think it presents some great advances for giving me my phone on the wrist and letting me easily transition to my running workouts.

One more thing about the Apple Watch Series 4 that is great for runners – fall detection. Yesterday, I took a really hard spill (feet got tangled up in a circle of wire I couldn’t see). With fall detection, had I been knocked unconscious, it would have called my wife and emergency services. Otherwise, you can just tell it you are ok. Falling on the side of the road can be dangerous and it has always been a concern of mine before about what would happen if some accident did occur. With the Apple Watch Series 4, that is a little bit easier to handle.

Alright, so which is better? I leave that to you! Both watches will help you as you run and offer encouragement to be more active. Both do a good job of giving you what you need for your run and both watches have the battery life to get you through a marathon – no matter how long it takes you.

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About the author


Charlie has been an avid traveler and runner for many years. He has run in marathons around the world for less than it would cost to travel to the next town - all as a result of collecting and using miles and points. Over the years, he has flown hundreds of thousands of miles and collected millions of miles and points.
Now he uses this experience and knowledge to help others through Running with Miles.


  • Hi Charlie,
    Very informative comparison. I am currently deciding which watch to upgrade to. I have the Garmin Foreunner 35. I’ve been testing some different apps and it seems that the garmin tracks my pace 20 seconds faster than Runkeeper. I was wondering what apps you prefer for pace accuracy? Thank you!!

  • Samantha,

    Unfortunately it doesn’t matter what app you use with Apple Watch – the accuracy isn’t as good as Garmin. I’m still not sure if this is hardware related or a software decision. I know from looking at the GPS data that Apple logs that it’s not consistent – unlike the option with Garmin to check every second. Apple tends to favour reducing battery.

    My advice is decide if you want a running watch or a smart watch with running features. If you race, or train on a track running intervals I feel the Garmin is essential. Main reasons are the lap button is so important (Apple watch does not have this), and the need to have accurate km/mile spilts is key for races. Apple watch can 5-20s off per km.

  • Stupid question sorry. When out for runs or workouts do you need to drag your phone with you in order to use all features of both watches?

    • Yes, unless you have a cellular version of the watch and a plan to go with it (with Garmin, that is only the Garmin Vivoactive 3 LTE version). That is just to use things like the apps with updated information or notifications. For things like tracking workouts and audio, you don’t need the phone.