Image source: Garmin

Garmin Forerunner 745 vs 645 Music: should you upgrade?

The Garmin Forerunner 645 Music was introduced in early 2018. Its headline feature was that it came with built-in storage for music. At the time, this was a first for the company. Since then music has become a staple part of the feature-set of watches in the Forerunner and Fenix line.

So it will come as no surprise that the Forerunner 745, which was introduced earlier this month, also comes with built-in storage. This is in addition to many other upgrades over the 645.

If you have the older device you might be wondering whether this might be a good time to upgrade. Garmin has stopped pushing the 645 through its website so it will probably look to phase out the watch in the next year or two. We are highly doubtful there will be an update in the form of a 655.

Right now, the 645 can be picked up at sizeable discounts over its RRP. But are the savings worth it? In this article we explain the differences between the Forerunner 745 and 645.


Garmin Forerunner 745 vs 645 Music: Design and hardware

Like all recent watches in the Forerunner line the duo is very similar in looks. The main distinguishing feature is the size.

The Forerunner 745 is the bulkier of the two measuring 43.8 x 43.8 x 13.3 mm. This compares to the 42.3 x 42.3 x 12.2 mm of the 645. Having said that, neither of these devices is very large and both are smaller than the 935/945 and most of the Fenix line.

Those with regular sized wrists should be just fine with the 745. If you have thinner wrists, the smaller size and weight of the 645 might be attractive.

Pretty much everything else about the look is the same if you ignore the cosmetic differences. One of these is the stainless steel bezel of the 645. It makes it look slightly more premium as compared to the fiber-reinforced polymer bezel of the 745.

Despite the smaller size, Garmin has included the excact same sunlight-visible, transflective memory-in-pixel display in both watches. It measures 1.2 inches (240 x 240 pixels).

Sensor-wise, once again there’s very little in it. The main addition of the 745 over the 645 is the SpO2 tech for measuring blood oxygen. The gyroscope, barometric altimeter, thermometer, compass, accelerometer, heart rate sensor are there on both.

garmin forerunner 745 vs 645 music should you upgrade - Garmin Forerunner 745 vs 645 Music: should you upgrade?
Forerunner 745 next to Forerunner 645 Music

But some of these have, of course, been upgraded to the latest generation. Not surprising as there is a two year gap between the duo. What you’ll also find on both is the built-in GPS/GLONASS/GALILEO and NFC for contactless payments.

Moving on to the all-important battery life and despite the extra sensors, the 745 outperforms the 645. While both can go about a week in smartwatch mode, the first can keep going slightly longer with GPS switched on.

You can find the exact specs below. The 645 also comes in a non-music version. The only difference there is that it lacks the built-in storage for music. The other specs are identical.

Forerunner 745 Forerunner 645 Music
Lens material Corning® Gorilla® Glass DX Corning® Gorilla® Glass 3
Bezel material fiber-reinforced polymer stainless steel
Strap material silicone silicone
Physical size 43.8 x 43.8 x 13.3 mm  42.5 x 42.5 x 13.5 mm
Display type Sunlight-visible, transflective memory-in-pixel (MIP) Sunlight-visible, transflective memory-in-pixel (MIP)
Display size 1.2″ (30.4mm) diameter 1.2″ (30.4mm) diameter
Display resolution 240 x 240 pixels  240 x 240 pixels 
Weight 47 g  42.2 g
Battery life (base model) Smartwatch Mode: Up to 7 days
GPS mode with music: Up to 6 hours
GPS mode without music: Up to 16 hours
Smartwatch Mode: Up to 7 days
GPS mode with music: Up to 5 hours
GPS mode without music: Up to 14 hours
Water rating 5 ATM 5 ATM
Memory/History 200 hours of activity data  200 hours of activity data 
Sensor GPS/GLONASS/GALILEO, barometric altimeter, compass, accelerometer, gyroscope, thermometer, heart rate, Pulse Ox GPS/GLONASS/GALILEO, barometric altimeter, compass, accelerometer, gyroscope, thermometer, heart rate
Connectivity Bluetooth®, ANT+®, Wi-Fi®  Bluetooth®, ANT+®, Wi-Fi® 
Plays and controls watch music Yes  Yes
Music Storage Up to 500 songs  Up to 500 songs
Garmin Pay Yes  No
Regular RRP $499.99 $449.99 (without music $399.99)

Garmin Forerunner 745 vs 645 Music: Activity tracking and smart features

Both of these watches are mid-range Forerunners. Which means they have a bit of everything and can be used to track your runs, bike rides and various other sports. This also means they will more than suffice as fitness and sleep trackers.

So lets jump straight to the differences. And while the hardware and sensors are similar, there are quite a few software based additions on the 745.

To start off, the SpO2 sensor allows for recording blood oxygen. This is performed mostly during the night while a person is asleep, but you can also take readings on demand.

We’ve created a list of all the additional features below. As you can see this includes the addition on the 745 of Body Battery, more detailed sleep statistics, 24/7 respiration metrics, extra performance data (Training Load Focus, Training Effect Labels and Heat and Altitude Acclimation) and abnormal heart rate alerts (both high and low). You don’t get any of this on the 645.

Essential readingTop fitness trackers and health gadgets

The 745 also has a New Daily Workout suggestion feature and recovery metrics are adjusted in real time depending on how well you are resting. Garmin has said this will come to the 945, 245 and latest Fenix watches but not to older devices.

Then there are Yoga and pilates workouts, extra outdoor recreation profiles and navigational capabilities, more cycling and swimming features (which includes tracking heart rate underwater). It’s a pretty long list of 745 extras, as can be seen below.

Forerunner 745 Forerunner 645 Music
Respiration (24×7) Yes No
Abnormal heart rate alerts (high/low) Yes No
Blood oxygen Yes No
Advanced sleep monitoring (sleep score & insights) Yes No
Body Battery Yes No
Group Live Track Yes No
Yoga and pilates workouts Yes No
Heat and altitude acclimation Yes No
Training load focus Yes No
Primary benefit (Training Effect labels) Yes No
Auto/Manual multisport activities Yes No
Round-trip course creator Yes No
Trendline Popularity Routing Yes No
Run profiles (Outdoor Track Running, Virtual Running)
Yes No
Outdoor recreation profiles (Hiking, Backcountry Skiing, XC Classic and Skate Skiing, Kayaking) Yes No
Barometric trend indicator with Storm Alert, ClimbPro™ Ascent Planner, Trail run auto climb, Future elevation plot Yes No
Cycling features (Mountain trail biking support, Bike lap and lap maximum power (with power sensor), Compatible with Vector™ (power meter), Power meter compatible, Advanced Vector support) Yes No
Swimming features (Open Water Swimming, Swimrun profiles, Auto rest, Time and distance alerts, Pacing alerts, Critical swim speed, Underwater wrist-based heart rate, Heart rate from external HRM) Yes  No

While the 745 does offer quite a bit more in terms of sports and fitness tracking, it is pretty much identical to the 645 when it comes to smart functionality. Both have an NFC chip for contactless payments. And if you buy the pricier Music variant of the 645 you’ll get storage that fits up to 500 songs on the device, which is the same as on the 745.


Garmin Forerunner 745 vs 645 Music: Verdict

The 745 and 645 Music are very similar watches in terms of the target market. They look alike and offer similar functions.

If you already own the 645 we don’t feel there’s enough additional functionality to justifying upgrading to the 745. Wait another year.

Unless, that is, you are itching to get a new watch. Hey, who are we to judge! If you are, you will get SpO2, the latest generation sensors, respiration data, more detailed sleep statistics, additional performance metrics, sports profiles and more. The battery life is pretty much the same, despite the slightly larger form-factor of the 745.

For first time buyers, you’re likely to find options to purchase the 645 and its Music variant at significant discounts. However it is difficult to recommend a watch that is some two years old and that even Garmin is slowly phasing out.

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