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Garmin Forerunner 645 Music review: A superb running watch

Our Rating :
£529.00 from
Price when reviewed : £399
inc VAT.

The Garmin Forerunner 645 Music is probably overkill for most runners, but it’s stylish and packed with features


  • Looks stylish for a running watch
  • Recovery and coaching functions are excellent
  • Garmin Connect app offers masses of insights


  • Pricey
  • Garmin Pay is distinctly limited

The Garmin Forerunner 645 Music is in a difficult position. For people dipping their toes into the world of running, there’s the Forerunner 30 and 35 at around £120, for amateur runners on a budget the Forerunner 235 does the job at £230, and for those wanting the very best, the Fenix range can set you back upwards of £600.

So where does that leave the £400 Garmin Forerunner 645 Music? Probably in a tough spot, which is a shame because, despite the huge collection of wearables on my desk, this is the one I inevitably turn to when it’s time to lace up and hit the road. 

Garmin Forerunner 645 Music review: What you need to know

As its name suggests, one of the main things the Forerunner 645 Music has going for it is music playback. There’s a regular Forerunner 645 that has no storage built in, too, in case you usually run with your phone. This version, however, is designed so you don’t have to.
Not only does it have space for around 800 songs, but it also has GPS and heart-rate monitoring built in, and support for Garmin Pay for contactless payments if your bank is supported (a big “if”, but more on that later).

Some of the key differences between this and Garmin’s cheaper running watches are the little extras it packs in. It uses heart rate and stress data to advise you on your training load to help get the most from your workouts and connects to Garmin’s Running Dynamics Pod (as well as to external heart-rate monitors) to provide deeper insights into your running technique, including vertical oscillation, stride length and ground contact time.

Both models of 645 are waterproof to 50m, but the Garmin 645 Music also builds on the cheaper Forerunner 235 with modes for cycling (indoor and outdoor) and swimming (indoor only).

Garmin Forerunner 645 Music review: Price and competition

At the time of writing, the Forerunner 645 Music goes for £400. The regular 645 without music (but with everything else) can be had for £350, which is a substantial saving. Not as much as buying the £250 Vivoactive 3 Music, however, which also supports music playback.
So what else is in that price bracket? Well, there’s the Polar Vantage V, which offers plenty of interesting features, including running power metrics straight from the wrist, but struggles with basic accuracy, so is probably one to give a miss. Alternatively, the Coros Apex is a fine multisport watch that starts at £270. Then there’s the all-new Suunto 9 (£450), which has class-leading battery life but lacks most of the smarts of the Garmin device. 

Garmin Forerunner 645 Music review: Design

Historically, running watches have been far more concerned with making everyone around you aware that you’re a runner than actually looking good. Thankfully, the Forerunner 645 is far less ostentatious and is quite happy to blend in with whatever outfit you’re wearing.
The 1.2in diameter screen is enclosed in a brushed metal frame and, while the included rubber strap slightly cheapens the look, it’s easily replaceable using the spring bar pins on the back. Personally, I’d stick with the rubber, though: it’s not overtly ugly and it would be a pain to switch from something less sweat-resistant every time you lace up for a run. Plus, it’s extremely comfortable for all-day and all-night wear, which is handy, given it does sleep tracking.
The size and clarity of the 240 x 240-pixel screen is such that it can show up to four data fields on a single screen, which is handy for at-a-glance information. For me, time, current pace, average pace and distance provides all the information I need.
There’s no touchscreen. Instead, the Garmin Forerunner 645 Music is controlled by five buttons – three on the left-hand side and two on the right. This may sound a touch dated but I’m personally a big cheerleader for physical buttons on running watches. Not only are touch controls fiddly when you’re exhausted but sweat and rain tend to interfere with how they operate, which isn’t ideal for a product that will inevitably come into contact with both rain and sweat.

Garmin Forerunner 645 Music review: Performance

Before I even get into the advanced features, I should say that the Forerunner 645 has the basics down to a fine art. Steps and sleep are diligently tracked and succinctly summarised in the excellent Garmin Connect app. Heart rate monitoring seems accurate, too, certainly when compared with the data pulled from a chest strap on the same run. And GPS is usually within 0.05km of a 5km parkrun, which is good enough for me.
Where it really comes into its own is its advanced features. For an amateur runner like me, the most useful of these are its recovery features. These not only give you a rolling VO2 estimate based on your heart rate and recovery time but they also tell you when you’re pushing yourself too hard and how long you should leave between training sessions based on their intensity. The nitty-gritty is hidden in the app and submenus of the watch, but if you’re actively improving, the watch will tell you mid-run when it spots you’re coping better than usual, which is a nice little morale boost. The watch will flash up your estimated recovery time at the end of a run, too.
Following a recent update to the Garmin Connect app, the Forerunner 645 also supports Garmin’s Coach 5km mode, which will guide you towards 5km goals, either in a couch-to-5km way, or through training you to achieve a specific time. Oddly, this feature is currently found only on Garmin’s more expensive watches (the Vivoactive 3 is the cheapest model with it), which is a strange move given beginners are unlikely to jump straight in by blowing upwards of £300 on a watch.

Having said that, there are heaps of other features you get for your money. Along with GPS and a heart-rate monitor, you’ve got GLONASS, an altimeter, a compass, a gyroscope, an accelerometer and thermometer all built in. If that’s not enough, it supports ANT+ and Bluetooth for connecting whatever third-party accessory you like, from footpods to chest straps.
Even without any extras, the 645 Music delivers a dizzying amount of data. Every single run I’ve recorded with the watch has offered the following data insights: average pace, average moving pace, best pace, average speed, average moving speed, maximum speed, total time, moving time, elapsed time, average heart rate, maximum heart rate, aerobic training effect, anaerobic training effect, average cadence, maximum cadence, average stride length, elevation gain, elevation loss, minimum elevation, maximum elevation, calories burned, average temperature, minimum temperature and maximum temperature.
And breathe.

You may find yourself scratching your head and wondering who on earth needs this much information. I’m with you, for what it’s worth – it’s definitely overkill for my needs. Still, all of the key data is neatly broken down into charts, and Garmin’s app (one of the best I’ve used) plays nicely with a handful of other services. Not many, but the key ones such as Strava and MyFitnessPal are there along with, slightly bafflingly, Office 365.
But what about music playback? Well, obviously being able to run without your phone or MP3 player is handy, and the fact that you can download the Spotify app from the Garmin IQ store (as long as you have a Premium membership) is also welcome. Setting it up is a bit of a fiddle and involves linking it to your Spotify account in the app, and then downloading music over Wi-Fi but at least it’s something you only have to do once.
You can put regular old MP3s on there as well or connect to Deezer or iHeartRadio, although, sadly, there’s no Audible app for those longer runs. Pairing the watch with headphones can be a bit flakey but once it’s in place it works well enough and certainly feels liberating.

You’ll almost certainly still want to take some money out with you in case of emergencies, however. That’s a bit disappointing if you see the words “Garmin Pay” on the box but the paucity of supported banks in the UK only slightly betters Fitbit’s pitiful British offerings. Santander is the only big name, but you should check the list yourself to be safe.
Sadly, the Forerunner 645’s battery life is also a little on the disappointing side. Garmin says you can expect a week of smartwatch use, or five hours if you rinse the GPS and Bluetooth music streaming to its fullest. I’d say that’s about right. I could pretty comfortably wear it for a week with a couple of half-hour runs thrown in before it needed a charge. However, charging is very fast and, pleasingly, the charger it uses is the same bulldog clip design that the company has on its other watches, which makes replacing a lost one or finding a spare pretty straightforward.


Garmin Forerunner 645 Music review: Verdict

There’s really not much bad I can say about the Garmin Forerunner 645 Music, other than the fact that it’s pretty expensive and – if you’re a casual runner like me – the data it provides is probably overkill. Most people could downgrade to the excellent Vivoactive 3 Music, saving nearly £200 in the process and still be very happy with the watch and the data gleaned.
But, despite this, I have lots of review watches on my desk, and when I lace up this is the one I instinctively grab. That says a great deal about the quality, comfort and style of the Garmin 645 Music. It’s one very special running watch.