While they are both highly respectable GPS watches, it’s worth mentioning the most important differences right from the get go.
- The Forerunner 645 is a designed primarily for runners. It contains most of Garmin’s latest features (eg Music Storage, Payments from watch) and every single running feature that Garmin has to offer.
- The Polar Vantage M is designed primarily for triathletes. In terms of value for money, it is arguably the best triathlon watch on the market right now.
- The FR645 has a barometric altimeter, music storage, contactless payments and various watchface customization options through Connect IQ. This makes it a better ‘smartwatch’.
- The Vantage M has open water swimming, triathlon mode, significantly more sports modes and a better optical heart rate monitor. It’s a more well rounded sports device, but not as good for running specifically.
Forerunner 645 vs Polar Vantage M - Key Similarities
Forerunner 645 vs Polar Vantage M - Key Differences
Features Unique to Forerunner 645
Music Storage & Music Apps - FR645 Only
This is a big difference between these two watches and a major win for the Forerunner 645.
Long story short, the FR645 gives you about 3.5GB of music storage to play with. You can also use the following popular music apps, even when you’re offline (the songs obviously need to be downloaded to your watch, which is super easy to do):
- Amazon Music
Advanced Running Dynamics
This is one of the main reasons the Forerunner 645 is such a good option for serious runners. Here is the full list of advanced running metrics that you can access with the FR645.
- Ground Contact Time – Time your foot spends on the ground with each stride)
- Ground Contact Balance – Symmetry between left and right foot)
- Vertical Oscillation – Degree of ‘bounce’ in your running motion.
- Vertical Ratio – the cost-benefit ratio with stride length.
- Cadence – Real time cadence data
- Stride Length – Real time stride length data
There is a small catch however. In order to unlock these metrics, you need invest in one of the following three Garmin Accessories.
- Garmin HRM-Run – Best for runners who want near perfect heart rate data.
- Garmin HRM-Tri – Best choice for triathletes (not a good fit for FR645 owners)
- Garmin Advanced Running Dynamics Pod – Best choice for people on a tight budget.
Galileo Satellite Tracking
Most people will be perfectly fine with GLONASS and GPS, but we have to mention the fact that the FR645 has Galileo tracking as well.
If you’re a Vantage M fan, do not despair. A Polar firmware update planned for October 2019 will see Galileo Satellite support added to the Vantage M and the Vantage V.
So right now this feature is limited to the FR645, but in a few short months, Galileo tracking will be available in both watches.
Payments from Watch - FR645 Only
Personally, I wouldn’t let this benefit sway my decision, but it is a nice bonus feature to have if you go with the Forerunner 645.
The ability to make payments from the watch can be pretty convenient if you want to leave your wallet at hope when you go to the gym or for a training session. Basically, this is a nice to have that you may or may not use.
Barometric Altimeter - FR645
The inclusion of a barometric altimeter means that the Forerunner 645 is better at measuring vertical movements than the Polar Vantage M.
The whole point of a barometric altimeter is to use changes in atmospheric pressure to help calculate vertical movements. During runs and cycles, this information is combined with GPS data to form a pretty accurate measurement of all movements (up, down, forward and back) during a training session or race.
This is not to say that the Polar Vantage M can’t measure vertical movements using the built-in GPS. Of course it can. It just can’t necessarily compete with the accuracy that the barometric altimeter of the Forerunner 645 brings to the table.
WiFi and ANT+ Support - FR645
Both of these features could prove to be deal breakers for some.
WiFi is super convenient for transferring training data from your watch to Garmin connect. It just makes the whole process of syncing information more seamless than it is if you rely on Bluetooth alone.
Then we have ANT+ support, which opens up an array of 3rd party accessories that can sync with your watch in real time. Most of these accessories are designed for cyclists, but there are a few that are designed for runners.
The main point is that ANT+ support means that your watch is setup to handle
Native Running Power Support + 3rd Party Running Power Support
The good news for Vantage M fans is that you can unlock running power with both Stryd and RunScribe.
However, the Forerunner 645 has one extra trick up its sleeve, because it supports Garmin Running Power, in addition to being compatible with Stryd and RunScribe.
There is just one extra thing that Garmin fans need to know. In order to unlock running power, you will need to invest in either the Garmin HRM-Run, the Garmin HRM-Tri, or the Garmin Advanced Running Dynamics Pod. ie You must purchase one the products mentioned above, to unlock Garmin running power on your FR645 device.
Features Unique To Polar Vantage M
Open Water Swimming - Vantage M Only
Given that the Polar Vantage M is a triathlon focused watch, it’s no surprise that it can measure open water swimming using the built-in GPS device. Naturally this is a major advantage of the Vantage M.
On this point, it’s worth mentioning that the Forerunner 645 can measuring pool swimming, and all of the SWOLF Metrics that you would expect. The bullet points below should help clarify any confusion when it comes to swimming modes:
- Forerunner 645: Pool Swimming with SWOLF metrics
- Vantage M: Pool Swimming with SWOLF metrics + Open Water Swimming
Triathlon Mode - Vantage M Only
This is by far the biggest strength that the Vantage M has over the Forerunner 645. The ability to measure all 3 disciplines of a triathlon makes it a more well rounded sports watch that you’re unlikely to grow out of.
I say this, because there are a large number of runners who may transition to triathlons over time. If you invest in the Vantage M, you know that it will have the legs to carry you through even the toughest triathlons. With 30 hours of GPS battery life, it’s safe to say that you would give up before your watch does. That’s definitely a good thing.
Over 80 Additional Sports Modes
If there’s one area that Polar truly shines, it’s the total range of sports modes that their watches can track. There are literally over 130 sports and activity modes that you add to the Polar Vantage M using the Polar Flow app.
This is not to say that the Forerunner 645 is a slouch when it comes to sports modes. In fact, you might find it difficult to find an activity that isn’t covered by the FR645. To help give you a more thorough understanding of the various sports modes, the table below should help:
Polar Vantage M vs Garmin Forerunner 645 - Sports Modes
|Forerunner 645 - Sports Modes||Polar Vantag M - Sports Modes|
|01) Strength Training||01) Strength Training|
|02) Cardio Training||02) Cardio Training|
|03) Elliptical Training||03) Elliptical Training|
|04) Stair Stepping||04) Stair Stepping|
|05) Indoor Rowing||05) Indoor Rowing|
|06) Yoga||06) Yoga|
|07) Running||07) Running|
|08) Treadmill Running||08) Treadmill Running|
|09) Indoor Track Running||09) Indoor Track Running|
|10) Trail Running||10) Trail Running|
|11) Cycling||11) Cycling|
|12) Indoor Cycling||12) Indoor Cycling|
|13) Pool Swimming||13) Pool Swimming|
|14) Skiiing||14) Skiing|
|15) Snowboarding||15) Snowboarding|
|16) XC Skiing||16) XC Skiing|
|16) XC Skiing||16) XC Skiing|
|17) Outdoor Rowing||17) Outdoor Rowing|
|18) Stand Up Paddleboarding||18) Surfing|
|19) Open Water Swimming|
|20) Triathlon Mode|
|21) 80+ Additional Sports Modes|
Better Optical Heart Rate Monitor
Before we dive into the details here, it’s worth mentioning that there’s no such thing as a perfect optical heart rate monitor. In other words, if you have extremely high hopes for the wrist-HRM, it would be best to dial those back a notch so your expectations can actually match up with reality.
Despite this forewarning, Polar’s precision prime optical (wrist-based) heart rate technology is the gold standard at this moment in time. This overview from Polar.com should give you a better understanding of the technology involved:
“Precision Prime is the only heart rate technology that utilizes three methods to provide accurate heart rate: nine optical channels using several colors and wavelengths of light, 3D acceleration and an electrical sensor that measures the quality of sensor-skin contact.“
This is not to say that Garmin’s elevate heart rate technology is that far off’s Polar’s precision prime technology. It’s just not quite as sophisticated.
The good news for runners is that running tends to be the one activity that most wrist-based heart rate monitors do a pretty good job of measuring.
Longer GPS Battery Life
This is already clarified in the data tables, but it’s worth repeating. The bullet points below should make the differences in GPS battery life pretty clear.
- Polar Vantage M GPS Battery Life – 30 Hours
- Garmin Forerunner 645 GPS Battery Life – 14 Hours
So as you can see, the Vantage M’s GPS battery lasts twice as long as the FR645 GPS battery. That’s a solid victory point for Polar’s unit.
So which one should you buy?
If you specialize in running
Go for the Forerunner 645. The inclusion of a barometric altimeter, Garmin’s advanced running dynamics and more options for recording running power will come handy as you progress in your running career.
If you're a triathlete
If you play loads of different sports
If cycling is your main sport
This is a tough one, but I would say the Forerunner 645 is actually the better option for cyclists. This is mainly because of the ANT+ support, which gives you access to a whole range of 3rd party cycling accessories that the Vantage M quite literally doesn’t support (because it lacks ANT+ connectivity).