This is truly a battle of the Forerunners.
On one side we have the Garmin Forerunner 645, which is essentially Garmin’s premium dedicated running watch (although the Forerunner 245 gives it a solid run for its money. You can check out that comparison here).
On the other side we have the Garmin Forerunner 945, which is arguably the best watch that Garmin has ever made in terms of price, value and total features (as of this writing).
But before we get into the nitty gritty, it’s worth mentioning the most important difference between these two watches. Here it is:
- The Forerunner 645 is designed primarily for runners
- The Forerunner 945 is designed primarily for triathletes
Garmin Forerunner 645 vs Forerunner 945 - Key Similarities
FR645
SEE PRICEFR945
SEE PRICEGarmin Forerunner 645 vs Forerunner 945 - Key Differences
Visual Summary of Features
Forerunner 645 - Features Summary
Forerunner 945 - Features Summary
Features Unique to the Forerunner 645
Apart from the silver bevel of the watch face and the less expensive price, the FR645 has no unique features when compared to the FR945.
This doesn’t mean that the Forerunner 645 isn’t awesome. It simply confirms just how powerful the FR945 really is. The product equation below should give you a pretty good understanding of what the 945 can do.
Garmin Forerunner 945 = Forerunner 245 + Forerunner 645 + Fenix 5 Plus
That’s not an overstatement. The FR945 can do everything the Fenix 5 Plus can do, and it has a few extra features that are only found in the FR245. You can see the full FR945 vs Fenix 5 Plus product comparison here.
Long story short, in the year 2019, the FR945 is Garmin’s star player.
Features Unique to the Forerunner 945
Open Water Swimming - FR945 Only
Only the Forerunner 945 gives you the ability to track your swims using the in-built GPS. The bullet points below should clear up any confusion on this point:
- Pool Swimming – FR645 & FR945
- Open Water Swimming – FR945 Only
Triathlon Mode - FR945 Only
This was mentioned at the beginning of the article but it’s worth repeating. The biggest difference between these two watches is that the Forerunner 945 has a triathlon mode.
This allows you to track each key discipline of a triathlon (swimming, biking and running) and switch between each discipline with the simple press of a button.
If you’re a triathlete, you really don’t have to do any further research. The FR945 has everything a triathlete could possibly need, and it has more technological features than the Garmin Fenix 5 Plus.
Body Battery Score - FR945
Garmin’s body battery score is one of the company’s key innovations in the last 12 months.
In essence, it uses data heart rate data, blood oxygen saturation levels, sleep quality and total exercise time to calculate your body battery level.
The higher your body battery charge, the harder you can push yourself during your next training session. On the other hand, if your body battery score is really low, it’s probably best to take it easy during your next few sessions, or to make time for some solid sleep sessions.
Garmin’s body battery score is likely to become a staple ingredient of all their future GPS watches and activity trackers. It’s built into the FR945 but sadly it’s missing from the FR645.
Pulse Oximeter - FR945 Only
The primary purpose of a pulse oximeter is to measure your blood oxygen saturation levels. That may sound great, but you’re probably wondering why it’s useful.
To cut a long story short, Garmin uses the Pulse Oximeter in the FR945 to measure your blood oxygen levels, which is then used to help calculate the following:
- Stress Tracking
- Advanced Sleep Monitoring
- Altitude Acclimation
- Body Battery Score
When Garmin first introduced the Pulse Oximeter in the Fenix 5 Plus, it was mainly used for altitude acclimation. However, their ability to leverage this technology has improved since then, and they are now using it to better measure the physiological state of your body. Hat’s off to Garmin for setting industry trends with this technology.
TOPO Maps - FR945
There’s a part of me that finds it difficult to believe that Garmin included TOPO maps with the Forerunner 945.
This particular feature has always been limited to the Fenix series, but that mould has officially been broken.
TOPO maps are basically beautiful representations of your surrounding landscape, displayed on the screen of your watch. You can use the maps to navigate pretty much any outdoor terrain (provided you have the Maps downloaded), which is super useful for hikers, trail runners, mountain bikers and adventure racers.
Golf Mode - FR945 Only
This is only relevant to golfers, but it’s a big deal for people who play 18 holes regularly. The Garmin Forerunner 945 gives you access to the following golf specific features:
- Yardage to front, middle and back of green
- Shot distance tracking (Garmin Autoshot)
- Digital scorecard
- Hazards and course targets
- Digital scorecard
As a super passionate golfer, this is a deal breaker for me. I would choose the FR945 over the FR645 based on this feature alone.
That being said, if you don’t play golf, you obviously shouldn’t let this feature affect your decision.
FR645 vs FR945 - Sports Modes
So which one should you buy?
There’s no question that the Forerunner 945 smokes the Forerunner 645 in terms of total features. It’s the better looking, more talented younger brother that will always make the FR645 envious.
But that doesn’t mean you should automatically buy the Forerunner 945, mainly because you have to pay quite a bit more for all those extra features.
In my opinion, it comes down to this:
Straight forward, Easy to read (with out all the meaningless pretty bullshit others put in) as well as a great comparison chart …..thank you
Excellent review. Comprehensive (enough) yet straight to the point. I own both watches. Have handed the 645 to my son.
All your comparison articles are very helpful and very straightforward. Keep rolling!
Great, thank you for this comparison! Still in doubt, but the differences are clear now.
Loved this. No fluff, direct, helped me so thank you!
Excellent review. Clean. Less is more.
I know the review focuses most on running, but since it does mention cycling (and even golf!!) there is a significant difference worth keeping in mind. The 645 does NOT support any kind of cycling power meter. So if you would like to see your cycling power, even occasionally (e.g. in a gym), you cannot do that with the 645, whereas you can with the 945. Ask me how I know 🙁
I’m gonna take a stab and say you bought the Forerunner 645 ?
In all seriousness though, I may look into adding a row for cycling power in future reviews, and update this particular review so cyclists are in the know.
And thanks for reading the blog.
Andy
You are correct, I bought it. Now, the lack of cycling power is not a big deal to me (I am mostly a runner, I do not have cycling power hardware on my bike), I discovered it just out of curiosity at the gym during an indoor bike sessions (when it was too cold to run or ride out), but I think it’s pretty important to some.
For the rest, thank you for putting together such great reviews, I was undecided about which FR to buy among all, and you helped me pick the 645 which has really been great for me