Fitness Gear

Stacking Them Up: New Apple Watch Series 4 vs Garmin Forerunner 645

apple watch series 4 vs garmin
Written by Charlie

Here is a spec matchup with the brand new Apple Watch Series 4 vs Garmin Forerunner 645 to see which one stacks up the best for your uses. They are now very similar to each other in some functions, price, and size so see the differences!

Several of the most-viewed posts on this site are about the Apple Watch and Garmin so I know people enjoy reading about these comparisons! Once I get the new Apple Watch Series 4, I will be doing real comparisons to a couple of similar Garmin watches. But, with preorders starting in less than 12 hours, I wanted to lay out the spec comparisons between the new Apple Watch Series 4 and the closest Garmin product.

Link: 4 New Features of the New Apple Watch Series 4 for Runners and Travelers

Stacking Them Up: New Apple Watch Series 4 vs Garmin

With the new Apple Watch Series 4 starting at $399, it places it pretty much in direct competition to the Garmin Forerunner 645. For more direct comparison, we will use the $449 Garmin Forerunner 645 Music.

To keep it fairly even, I am using the 44mm Apple Watch Series 4 GPS ($429) and the Garmin Forerunner 645 Music ($449). Note that both manufacturers use fancy language to describe the glass face which is really different kinds of strengthened glass. Neither watch uses a Sapphire crystal (you need to move up to the Garmin Fenix 5 Sapphire or the 5 Plus Sapphire for Garmin or the Apple Watch Stainless Steel – both sets are similar prices).

SpecificationApple Watch Series 4Garmin Forerunner 645 Music
Battery LifeGeneral Use: 18 Hours
GPS Use: 6 Hours
GPS w/Music: 5 Hours?
General Use: Up to 7 Days
GPS Use: Up to 14 Hours
GPS w/ Music: Up to 5 Hours
Music Storage16GB of storage3.5GB of storage
Water ResistantUp to 50 MetersUp to 50 Meters
Native Sleep TrackingNoYes
Built-in Heart Rate MonitorYesYes
Always-On DisplayNoYes
Multi-Sport CapabilityYesYes
Glass materialIon-X Strengthened GlassChemically Strengthened Glass
Weight36.7 Grams42.2 Grams
Dimensions44 x 38 x 10.7 mm42.5 x 42.5 x 13.5 mm
SensorsOptical heart sensor, electronic heart sensor, gyroscope, barometric altimeter, accelerometerOptical heart sensor, barometric altimeter, compass, gyroscope, accelerometer, thermometer
Compatible with iOS and AndroidNoYes
Switchable watch bandsYesYes (20mm bands)

Again, this is just to give you an idea of the feature sets on both these watches. I will be doing comparisons when I get my hands on the Apple Watch but hopefully this will help you if you are trying to decide if you are going to buy an Apple Watch Series 4 tomorrow.

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About the author


Charlie has been an avid traveler and runner for many years. He has run in marathons around the world for less than it would cost to travel to the next town - all as a result of collecting and using miles and points. Over the years, he has flown hundreds of thousands of miles and collected millions of miles and points.
Now he uses this experience and knowledge to help others through Running with Miles.