Deciding between Garmin Forerunner 245 and 645

How does the newly released Garmin Forerunner 245 compare to the older Forerunner 645? That’s the question I asked myself when I went looking for a new watch and this article will guide you through my findings.  For the past few months I’ve been thinking about replacing my Garmin Vivoactive 3. The touchscreen was starting to bug me, I can’t count the amount of times I accidentally pressed something on that screen. And, I was interested in more running data. The Vivoactive 3 provides basic data, but the more I was running the more I got interested in performance data. I am very satisfied with Garmin in general and since I’ve also started the Garmin Coach half marathon plan, I have not considered other brands.  What am I looking for in a new watch?
    • All the basics the VA3 has: GPS, heart rate, etc.
    • Advanced running data
    • Suitable for every day use
    • Music
The most complete option would be the Fenix 5S Plus. It looks awesome, has everything I could need and some more. But, it also has a price tag of about € 650,- and that is a little more as I’m willing to spend. In the back of my mind the decision was already made, the Garmin Forerunner 645 Music has everything I want and it looks almost identical to the Vivoactive 3, which is a plus point in my mind. And, it has buttons instead of a touchscreen. Done deal! But then Garmin went ahead and announced three new watches: Forerunner 45Forerunner 245 or 245 Music and the Forerunner 945. The Forerunner 245 Music and the 645 Music are similar in features and price, so I had a dilemma to solve. This article will guide you through my research and thought process that led me to eventually buy the Forerunner 645 Music.

Current prices on Amazon: 

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Fitness features

Both the Forerunner 245 Music and the 645 Music are equipped with a LOT of awesome features. Find and compare them for yourself one the Garmin website: 245M and 645M.

The 645 tracks 19 different sport profiles and the 245 only 16. There are some differences in the profiles, but the main thing the 645 has that the 245 doesn’t is: skiing, snowboarding, XC skiing and stand up paddle boarding.

Forerunner 645 (Music)
Barometric altimeter. More accurate elevation tracking as well as stair climbing. 
Lactate Threshold. The estimated level of effort or pace (only when paired with a chest heart rate monitor).

Strava Live Segments. Notifications on your watch when you approach segments of interest (Strava Summit required).

Forerunner 245 (Music)

Pulse OX. Wrist-based pulse oximeter to gauge the saturation of oxygen in your blood. Knowing your oxygen saturation can help you determine how your body is adapting to exercise and stress.
Firstbeat race predictor. Improved race time predictions. While the 645 uses VO2Max only to predict your race times for 5K, 10K, half and full marathon, the 245 also takes long- and short-term trends in your weekly running mileage totals into account.

Update 11-01-2020
At the end of 2019 a new feature was rolled out to the Forerunner 245: PacePro. It’s an interesting feature that will help you with pacing during your race. You are able to set up your race strategy in the Garmin Connect and in combination with Garmin Courses it can even factor in elevation. During your race your watch will show your target pace for each split and how you are performing compared to the target you’ve set. 
This feature will not be available on the Garmin Forerunner 645. 


Battery life

The battery life in smartwatch mode or GPS mode with music doesn’t vary much between the two watches, but the GPS mode without music does show a big difference. The 245 will give 10 hours longer battery life with GPS and without music. 

Forerunner 645 (Music)

Smartwatch Mode: Up to 7 days
GPS mode with music: Up to 5 hours
GPS mode without music: Up to 14 hours

Forerunner 245 (Music)

Smartwatch Mode: Up to 7 days
GPS mode with music: Up to 6 hours
GPS mode without music: Up to 24 hours 

Smart features

Garmin Pay is only available on the Forerunner 645. This allows you to make payments without bringing a card, phone or cash. Availability depends on location and banks compatibility. 
Assistance alert and crash detection are only available on the Forerunner 245. This will automatically send an alert to selected contacts when your watch detects a fall or it can be activated manually with a button press. 


The design of both watches is similar. Both have a circular design, but while both watches have a bezel, they are not made of the same material. The 645 has a stainless steel bezel available in different colors, while the 245 has a bezel made of fiber-reinforced polymer, available only in black. 

Each watch comes with Corning Gorilla Glass 3 and a 20 mm silicone quick release watchband. 

Size and weight Forerunner 645 Music: 42.5 x 42.5 x 13.5 mm / 42,2g
Size and weight Forerunner 245 Music: 42.3 x 42.3 x 12.2 mm / 38,5g

While the Forerunner 645 is available with different color bezels, the watch itself is always black. The Forerunner 245 always has a black bezel, but the watch itself comes in either black or white. Both watches can be ordered with different color watchbands as well. 


For me there wasn’t one feature that the other watch was missing that I really needed or wanted. Based on all this data, I couldn’t make a decision. Both watches are very complete for both running, other sports and every day life. So, I made looks the deciding factor. I went to a Garmin store that has all Garmin watches on display to touch and play around with and I went with the watch that looked and felt the best in my opinion. The Forerunner 645 Music has been in my possession for two weeks at the time of writing this and I have no regrets. It is a great watch. I’m sure I wouldn’t have thought differently if I had gotten the Forerunner 245 Music though. Whether you should buy the 645 or the 245 all comes down to personal taste, and my taste went with the Forerunner 645 Music.
Update 11-01-2020

Knowing what I know now I would probably have chosen the Forerunner 245. Partially because of the addition of the PacePro feature, partly because this is a sign the Forerunner 645 is no longer getting any new features, while the Forerunner 245 will probably receive more cool, new features. 

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