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Garmin Forerunner 645 Music Review

If you want a lightweight, feature-packed watch that lets you leave your phone at home, go for the Forerunner 645 Music
Garmin Forerunner 645 Music
Photo: Garmin
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Price:  $450 List | $291.93 at REI
Compare prices at 2 resellers
Pros:  Compact and lightweight, accurate, extensive features
Cons:  Clunky music upload, short battery life with music, expensive
Manufacturer:   Garmin
By Joanna Trieger ⋅ Review Editor  ⋅  Jun 7, 2018
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  • Features - 35% 8
  • Ease of Use - 25% 7
  • Battery Life - 15% 7
  • Accuracy - 15% 8
  • Design - 5% 8
  • Ease of Set-up - 5% 6

Our Verdict

New to the field in 2018, the Garmin Forerunner 645 Music is a compact, feature-filled GPS smartwatch that can store up to 500 music files locally. Users can bliss out to music on the run and leave their phones behind. We definitely enjoyed this function, but the process for uploading music is very clunky and needs improvement. Aside from that, the 645 Music is simple to use, and we were impressed by its deep well of features and its decent battery life given its small size.

Our Analysis and Test Results

Music in your ears without a bulky phone in your pocket — sounds great, right? That's what Garmin promises with its new Forerunner 645 Music, and it delivers, for the most part. While we weren't blown away by this model's music function, it gets the job done, and the rest of the watch's features are rock-solid.

Performance Comparison

Easy to use, the 645 Music lets you get out on the trails in a hurry.
Easy to use, the 645 Music lets you get out on the trails in a hurry.
Photo: Joanna Trieger


Given its relatively small size, the Forerunner 645 Music has an impressive list of features. Most obviously, this is the only watch in our test group that can store music. This watch also has Garmin Pay, so you can link a credit card to your watch and use it to make purchases in most establishments that accept contactless payments

Ease of Use

Like all the Garmin devices in our test group, we found the Forerunner 645 Music to be intuitive and easy to use. Its five buttons make it easy to navigate through the features, activities, and menu screens, and the data that can be accessed and displayed on the watch itself is customizable.

Navigating through the Forerunner 645 Music's data screens is easy...
Navigating through the Forerunner 645 Music's data screens is easy and intuitive. Here, our tester checks out his heart rate after a trail run.
Photo: Joanna Trieger

Syncing the device with a smartphone was simple, and once connected, our activities uploaded to the Garmin Connect app automatically. Garmin Connect is also easy to use, allowing users to view their daily activities and their progress over time with a series of intuitive widgets.

Garmin Connect is intuitive and easy to use. Shown here is a sample...
Garmin Connect is intuitive and easy to use. Shown here is a sample activity displayed in the full web version of the app. The data you see on this screen is customizable, and you can dive deeper into each metric.
Photo: Joanna Trieger

We were slightly less impressed with the ease of uploading music to the Forerunner 645. For files stored locally on your computer (MP3s, etc.), uploading is reasonably simple, if a bit clunky. It requires connecting the watch to your computer via the charger cable and using the Garmin Express desktop app to navigate to your audio files. From there, the upload is a speedy process.

To upload via a streaming service — well, first, prepare to be disappointed. Most popular music streaming services, including Pandora, Spotify, and Apply Music, don't sync with this watch yet. You can upload playlists from iHeartRadio, but you'll have to pay a $9.99/month All Access subscription fee for the privilege. As non-iHeartRadio users, we weren't super stoked at having to switch streaming services for the sake of the watch. You can upload playlists created on iHeartRadio to the Forerunner 645 Music over WiFi, but the watch demands that you plug it into a charger while uploading. All in all, the process works, but it feels old-fashioned and labor-intensive compared to the seamless user experience elsewhere in the watch.

Once we had some content uploaded, listening to music during activities was a breeze. You can access music controls from any screen by holding the "Down" button, and it was easy to navigate between playlists and songs while running and riding. Before testing this watch, we read lots of complaints about unexpected mid-workout reboots, music refusing to sync, and music cutting out during workouts. We did find that we could get the music to cut out if we put our watch wrist all the way under the bike seat while out for a ride, but…why would you do that? Otherwise, we didn't have any issues.

Without playing music or using GPS tracking, the Forerunner 645...
Without playing music or using GPS tracking, the Forerunner 645 Music will stay charged during a multi-day backpacking trip.
Photo: Joanna Trieger

Battery Life

For normal day-to-day use (wearing the device 24/7 and tracking 1-2 hours of GPS activities per day), the Forerunner 645 Music needed charging every three to four days without music. Adding music during activities drained the battery quickly, so we had to charge the device every one to two nights.

When we tracked a continuous GPS activity until the battery died (again, without music), the 645 lasted 13 hours, which impressed us given its size. By contrast, the larger Forerunner 935 lasted over 21 hours. If you're an ultrarunner, you'll likely outrun the 645 Music's battery, and even regular marathoners may kill the battery if they listen to music throughout their race. But for those who just want tunes during their shorter training runs, the Forerunner 645 Music's battery life is sufficient.

We know we ran precisely half a mile. The Forerunner 645 Music agrees.
We know we ran precisely half a mile. The Forerunner 645 Music agrees.
Photo: Joanna Trieger


We took the 645 Music out for two sets of two laps on a standard 1/4-mile outdoor track and got perfect 0.50-mile readings both times. All the watches we tested in 2018 were either dead accurate or were just 0.01 miles (2%) off during this test, while the 2017 test group had much wider variations.

We analyzed our GPS tracks after each activity with the 645 Music, and generally, the tracks were accurate based on our known routes. While running, the paces displayed on the watch face lined up with our expectations based on years of running experience.

While the Garmin Forerunner 645 Music (right) is significantly...
While the Garmin Forerunner 645 Music (right) is significantly smaller than the Forerunner 935 (left), the display is a similar size.
Photo: Joanna Trieger


Weighing in at just over 42g, this watch is among the lightest in our test group. The 645 Music is pleasantly compact, with a smaller face and a slightly slimmer profile than its cousin, the Forerunner 945. Note, though, that the display on these two models is the same size, so you won't have to squint to enjoy the 645 Music.

The 645 Music lies flat when it's not on your wrist, and its band has quick-release pins so you can remove it easily if you want to slip the watch face into a tight pocket.

Even on a cloudy day, the Forerunner 645 Music accurately captured...
Even on a cloudy day, the Forerunner 645 Music accurately captured our track along with winding course.
Photo: Joanna Trieger

Ease of Set-up

Like all the Garmin devices we tested (and most of the other devices, as well), the 645 Music is simple to set up. It's as easy as downloading the Garmin Connect app to your phone, turning on the watch, and following the instructions on the two screens. Set-up took about five minutes from start to finish, and we didn't even need to charge the watch before using.

LOL. We wish this were accurate, but it isn't, especially for the...
LOL. We wish this were accurate, but it isn't, especially for the longer distances. Your Garmin will need to collect a few weeks' worth of data before it can accurately predict your race times.
Photo: Joanna Trieger

Like the other high-end Garmins in our test group, some of the 645 Music's features require a period of use before they become fully functional. Though the watch provides training status information after about a week of use, some aspects — like the race predictor, pictured below — needed more time to improve accuracy.


Taking into account the other options on the market, we think the price is steep for this watch. For just $50 more, you can enjoy much better battery life and improved navigation capabilities from the Garmin Forerunner 935.


Even without its innovative music capabilities, the Forerunner 645 Music is a great GPS watch. It has a wide range of features and a pleasantly slim design, and its battery life is solid if you plan your music and GPS use strategically. The introduction of music into this model feels a little premature, so you might be happier waiting a year or two for this technology to improve. But if you do spring for this watch, we bet you'll like it.

Joanna Trieger