Garmin Forerunner 645 Music Review

There's no shortage of fitness trackers on the market, but there are relatively few that allow you to lace up and hit the pavement without needing your phone nearby.

At $449.99, the Garmin Forerunner 645 Music certainly isn't cheap, but it delivers a ton of functionality for the price.

It has sensors that track everything from your steps and heart rate to your location and temperature.

It also has NFC so you can leave your wallet behind, and holds up to 500 songs, so all you need is a pair of Bluetooth headphones and you're good to go.

If you love to exercise outdoors and want to take a deep dive into your fitness metrics, you'll be hard-pressed to find a more comprehensive tracker.

Functionality First

The Forerunner 645 Music uses a traditional sports watch design that isn't unattractive, but is definitely more casual than elegant.

The default black or pink silicone bands are textured, but don't feel particularly sturdy, especially given the price.

On the plus side, you can swap them out for any 20mm band. Featuring a 1.2-inch round display bordered by a stainless steel bezel, the watch face is relatively thin and weighs 1.5 ounces with the strap, making it comfortable for most wrist sizes.

Although it looks like it, the Forerunner 645 doesn't have a touch screen.

Instead, its color display is a transflective memory-in-pixel screen, which is a fancy way of saying it's easily visible in sunlight.

It has a resolution of 240 by 240 pixels, which is clear enough, though text looks a little jagged.

You navigate through menus using the five buttons located around the display—three on the left side and two on the right.

The top left button controls backlighting, while the bottom two scroll up and down.

But that's not all.

If you hold down the top button, it brings up a menu where you can turn the watch off, sync, toggle Do Not Disturb mode, or lock it, as well as access the wallet, stopwatch, timer, and Find My Phone feature.

If you hold the middle button you can view remaining battery life, change the watch face, edit alarms, view your activity history, and manage settings.

You can also press it once from the main screen to scroll through your widgets.

Lastly, holding down the bottom button brings up music controls.

The buttons on the right side are much simpler.

The top one is used to start and stop activities.

It also doubles as a select button.

The bottom button returns you to previous menus.

If this system sounds convoluted, it's because it is.

The learning curve is fairly steep, but the payoff is that you get far more battery life than you do with a power-hungry touch screen.

In standard mode, the Forerunner 645 gets an estimated seven days of battery life.

With GPS on, you get up to five hours with music playback and 14 hours without.

In testing, I wore the Forerunner and logged about two hours of exercise over two days, during which time I only used 18 percent of the battery.

The Forerunner has an impressive array of sensors, including an accelerometer, a barometric altimeter, GPS with GLONASS, a compass, a gyroscope, an optical heart rate monitor, and a thermometer.

That allows it to measure everything from step counts and elevation to heart rate zones and sleep.

It's also water resistant to 165 feet (or 5ATM), making it safe for the shower and pool.

Leave Your Phone at Home

Unlike the Apple Watch Series 3, the Forerunner doesn't support phone-free LTE connectivity.

That means you're out of luck if you want to access the web or take calls from your wrist.

That aside, the Forerunner delivers solid phone-free performance for outdoor activities.

While you'll mostly interact with the Forerunner through the mobile Garmin Connect app (available for Android and iOS), you'll need the to use the desktop Garmin Express app to load songs onto the device.

Garmin Express lets you easily drag and drop up to 500 songs onto the Forerunner, which you can listen to through a pair of Bluetooth headphones.

If you're an iHeartRadio user, you can download the app from the Garmin Connect IQ store to load your playlists.

If you don't care about music functionality, you can save $50 on the standard Forerunner 645.

You can set up Garmin Pay directly from the mobile app, provided your bank has a partnership with Garmin.

The process is easy enough—you either scan your card or enter your details manually in the app.

Unfortunately, none of my credit or debit cards were issued by a partner bank, so I was unable to test this feature.

If NFC payments are important to you, be sure to check the list of supported banks before buying in.

Fitness Tracking and Accuracy

Whereas some apps, like Fitbit's, simplify your data so you can easily understand it at a glance, Garmin has always opted for a "more is better" approach.

That remains true here, as you can measure and access the usual stats like steps, stairs climbed, calories burned, and heart rate, as well as less common metrics like stress and VO2 Max.

When you look at the data for an individual exercise session, you can also look at your best pace, average moving speed, run cadence, stride length, and temperature, among other stats.

This is valuable for serious training, but less useful if you just want to keep an eye on your general activity levels.

See How We Test Fitness Trackers

When it comes to accuracy, the Forerunner 645 delivered superlative performance in testing.

On a one-mile treadmill walk at 3.5 miles per hour, it recorded 2,133 steps to a Yamax SW-200 Digi-Walker's 2,136 steps.

On a one-mile treadmill run at 5mph, the Forerunner logged 1,891 steps to the Digi-Walker's 1,899 steps.

That's a negligible difference of 0.1 and 0.4 percent, respectively.

Indoor distance tracking was also spot-on, with the Garmin logging exactly one mile for my walk, and 1.12 miles for my run.

I was impressed by the option to edit my distance after my run so I could calibrate the Forerunner to the treadmill itself.

Where the Forerunner really shines is in its outdoor performance.

The screen is very easy to read in direct sunlight, and GPS tracking is accurate.

On a one-mile outdoor run without my phone it logged 1.1 miles, and on a 0.5-mile walk in the city, it logged 0.56-mile.

I never had an issue quickly getting a GPS signal, and even with music playing, I still had plenty of battery left after 30-minute test sessions.

The Forerunner also did well when it comes to heart rate.

On both treadmill tests, it remained within five to 10 beats per minute of the Polar H10 chest strap, and was able to reflect warm up and cool down times without noticeable lag.

While the Forerunner can track light and deep sleep, it doesn't give you much insight into your sleeping patterns the way Fitbit does.

Also, I found it sometimes confused tossing and turning with light sleep.

On a night that the Fitbit Versa logged 4 hours and 55 minutes of sleep with 51 minutes awake (accurate, by my own restless account), the Forerunner reported a restful 6 hours and 2 minutes of sleep with only 3 minutes of wakefulness.

Comparisons and Conclusions

Long battery life, in-depth metrics, excellent accuracy, and a strong phone-free experience make the Garmin Forerunner 645 Music one of the best trackers we've tested for outdoor training.

If you spend a lot of time prepping for marathons, triathalons, or endurance courses, it could be worth the hefty investment.

If you aren't a serious athlete, however, the Apple Watch Series 3 and Fitbit Versa are good alternatives.

They both provide a streamlined view of your health and are less expensive.

That said, the Versa requires you to bring your phone along for GPS and music, while the Apple Watch isn't quite as comprehensive in the fitness department.