Garmin Forerunner 645 vs. Fenix 5 – Comparison of 2023

Sports watches have come a long way since their invention. From just telling the time, syncing notifications from smartphones, and providing basic data about tracking activities to providing advanced data for training has been a breakthrough for athletes.

If you are an athlete or you love to stay fit, then a sports watch is a must-have item for you. Nowadays, one of the top brands, besides Fitbit and Apple, is Garmin.
But which one to get out of so many options in the market? This article will provide you with an account of Garmin 645 vs. Fenix 5, two of Garmin’s finest watches, to help you answer the question.
Garmin 645 vs. Fenix 5 – Comparison in 2023
Garmin Forerunner 645
The Garmin Forerunner 645 is a multi-sports watch with unique features to keep your training smooth and successful.
This watch can be set to various sports such as running, cycling, and swimming – both indoor and outdoor.
It provides you with an advanced set of data, which, if you can use correctly, can get you the next gold medal.
In addition to the basic data like heart rate and counting steps, it can provide you with ground contact time, calories burned, longitudinal oscillation and ratio. In swimming mode, you can track your speed, strokes, and many more.
Moreover, this watch enables you to connect with wifi and thus never be out of reach.
With its ability to store up to 500 songs, training can become more enjoyable and energetic than ever.
This device is also equipped with another unique feature, and that is the option of contactless payment.
Wherever you are and whatever you buy, you can pay for it via a cooperating bank card by pressing a small button on your watch. This gives you the freedom to step out cashless.
The watch runs on a single CR2 battery, with a battery span of 7 days in smartwatch mode and 5 hours in GPS mode, including music.
It is lightweight and comfortable to wear, weighing about 1.5 ounces with the dimensions of 1.7 by 0.5 by 1.7 inches.
PROS
CONS
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Garmin Fenix 5
The Garmin Fenix 5 is an elegant sports watch that functions for a variety of sports, including running, cycling, swimming, skiing, golf, and even paddle sports.
Such a large variety is rarely seen in even the high-end watches.
In addition to smart notifications, it brings you a refined set of data to monitor your progress and comes with the ability to estimate your best outcome.
The watch gives you a constant measure of your heart rate without the need of a chest strap.
It also informs you of your VO2 max, lactate levels, stride length, distance covered, speed, longitudinal ratio and oscillations, and other data about your chosen sport.
Moreover, it helps you monitor your sleep and calories burned and the effectiveness of your training sessions.
This watch is slightly heavier than some of Garmin’s other productions, with a weight of about 2.4 ounces and it measures to about 0.6 by 1.9 by 1.9 inches.
Though the watch cannot connect with wireless Internet, it does support connectivity via Bluetooth, allowing you to sync all the notifications from your phone and connect to its IQ store.
However, an internet connection can be achieved with the Saphire edition of the watch.
PROS
CONS
With all this information in mind, let’s compare the two products and see where the main differences lie.
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Difference Between Garmin Forerunner 645 and Fenix 5

As we are going to weigh the features of both these items here against each other, it will be easier for you to pick between them.
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Battery Span
Although the two watches run on the same battery – a single CR2 battery, one has a battery span considerably shorter than the other.
The battery life of Garmin 645 is 5 hours in GPS mode with music and 7 days in smartwatch mode.
On the other hand, Fenix 5 has a battery life of 24 hours in GPS mode and 14 days in smartwatch mode.
Having a long battery span is important when you are out hiking new places or when you can’t charge your device often.
Sports
The Garmin 645 offers track running, swimming, cycling, and strength training quite efficiently, with advanced data without the need for a chest strap.
If you do add the chest strap to your training sessions, you can extract the full function that you can get from a smartwatch.
Fenix 5, however, offers many more options. You can track running, cycling, swimming, golf, skiing, and paddle sports.
With the correct setup, you can get all the data you need to improve in your choice of sport.
Both the watches are waterproof, but they differ in the extent. The Fenix 5 can withstand double the water pressure than a Garmin 645.
Combined with its stroke counter, the Fenix 5 maybe a better option in this regard, if you are a swimmer.
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Comfort
The Garmin 645, weighing almost half the weight of Fenix 5, is more comfortable to wear for a longer period.
Frequently Asked Questions
Which of the two is better for a hiking trip?
If you plan to wander in new places or spend the day hiking with friends or alone, Fenix 5 is a better option.u003cbru003eu003cbru003eIt has a longer battery life and connects to GPS faster. The watch can also show maps of your current location and is also equipped with a feature that can help you find your way back if you get lost.
Can you play music with Fenix 5?
This watch itself cannot store and play music, unlike the Garmin 645.u003cbru003eu003cbru003eBut you can connect it to your phone via Bluetooth and control the music player from the watch.
Will the GPS work if it’s covered under the sleeve?
The watch being covered under the shirt or hoodie will work just fine.u003cbru003eu003cbru003eThe sensors are strong, and they record data quite accurately. However, the signal may be cut off if it’s covered with thick metal.
Which of the two should I Buy?
This depends on your purpose. If you are a runner or a cyclist or just like to monitor your fitness level, you can buy the Garmin 645 and enjoy the options of music and cashless payment.u003cbru003eu003cbru003eIf you’re a swimmer or like to wander around in new places and don’t mind the heavyweight, then the Fenix 5 is for you.
Can I track my weight?
The Garmin 645 has no built-in option for this, but you may be able to do that if you download such an app from their IQ store. However, Fenix 5 comes with a built-in weight tracker.
Conclusion
None of these two watches are limited to the options they come with, as you have seen in the comparison of Garmin 645 vs. Fenix 5.
You can improvise with the help of numerous apps that can be downloaded. They also cost nearly the same. So, get the one that is most useful to you and train your way to fitness.