Updated: June 24th, 2019
Garmin Forerunner 45 vs 245 vs 645 vs 945

If you are a runner, chances are that you have heard of Garmin and their GPS running smartwatches. They make some of the best GPS running watches out there and regularly top our charts of best GPS running watches and offer a wide variety of running watches for every runner and every budget.

They recently announced 5 new GPS watches to update their Forerunner series, one of the most popular and reliable series: the Garmin Forerunner 45, 45s, 245, 245 music and 945.

These come complement perfectly the Garmin Forerunner 645, a mid-to-high range performance running watch for serious runners that was released in 2018. It costs $399.99 and also offers a music option for an additional $50. You can check out the review of the Garmin 645 here.

The new lineup is replacing the “35” series (35, 235, 635, 935) that was released back in 2016. The 35 series watches are now on sale, so if you don’t need the latest and greatest, you might be interested in grabbing one of those before they go out of stock. You can check out the review we wrote on this great lineup a couple years ago here.

Garmin Forerunner 45 vs 245 vs 645 vs 945
The updated Forerunner lineup brings loads of useful new features such as integrated music, full-color on-board maps (for the 945), advanced training, and safety contact. Once again, Garmin took the best of what makes the Forerunner Series a lasting success, and added even more features.

This can make it hard to know which one is right for you, your budget and your fitness level. Luckily for you, we took a look at the new 45 series and broke it all down for you. So let’s find out if all the latest advancements are worth it!

The 5 new Garmin Forerunner series GPS watches

All of the new watches have a similar five-button design which is easy to operate in all weather conditions. They all come with a sunlight-visible color display, an always-on display, a wrist-based heart rate sensor, and smartphone notification compatibility (both Android and iPhone).

Garmin added a nice safety feature that automatically detects incident during your activities and sends your geolocation to up to three chosen emergency contacts. That means that if you crash and are unconscious, the watch is able to alert someone by itself. All you need is to pair it via Bluetooth with a smartphone with a data plan. This is essential for anyone who trains in the mountains for example. Additional safety measures include Assistance, LiveTrack and Live Event Sharing (so friends and family can follow you).
Garmin Forerunner 45 vs 245 vs 645 vs 945

They have also upgraded their navigation system with multi-satellite network capability now supporting GLONASS and Galileo on top of GPS.

All of them are compatible with Garmin Coach if you like free training plans and getting advice from Garmin’s expert coaches. And it’s not just for tracking running, the GPS watches all come with a dozen profiles for different activities.

As a nice bonus, all the new watches are water rated for swimming (5 ATM). They also come with a feature I love: Body BatteryTM. It rates you energy reserves at any time during the day using a number from 0-100. It does so by tracking things like heart-rate variability (HRV) sleep, stress or physical activity.

So, besides price, what sets them apart? Let’s dive into each GPS watch’s specs and functions.

Garmin Forerunner 45 and Forerunner 45S

Garmin Forerunner 45 vs 245 vs 645 vs 945
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The 45s is simply a smaller more compact version, although the regular 45 is far from being bulky. The case size of the 45s is 39mm and 42mm for the 45.

In both sizes, the watch offers a battery of up to 7 days in smartwatch mode and 13 hours in GPS mode. That’s the same battery life as its Forerunner 35 predecessor but while boasting a full-color display.

They are customizable with 4 color options for the bands and customizable watch faces.


  • Bang for your buck
  • Compact and Lightweight (32g and 36g respectively)
  • Color display
  • Handy controls for the music on your phone


  • No swimming tracking
  • No on-board music
  • Bands cannot be changed

Who is it for?

Everyone really. It is a lightweight and affordable entry-level GPS watch that packs all the basic features and much more. As long as you are happy with everyday wellness/heart rate/stress tracking and basic training data, this watch has everything you need. Although it does not offer on-board music, you can pair it with your phone to control the music. At $199, it is a well-rounded entry-level GPS smartwatch.

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Garmin Forerunner 245 and Forerunner 245 Music

Garmin Forerunner 45 vs 245 vs 645 vs 945
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At 43mm wide and weighing 38.5 g, this GPS watch is still impressively lightweight. It packs all the features of the Forerunner 45 and many more.

The music edition – for an extra $50 – can store up to 500 songs and can sync directly with music streaming services (like Spotify). It also supports Wi-Fi for that purpose.

The bands come in 5 color options and are Quick Release bands so you can easily change them.
The battery life is up to 7 days in Smartwatch Mode, up to 24 hours in GPS mode without music and up to 6 hours in GPS mode with music.

It has some added sensors, such as a compass and a pulse oximeter to track you blood oxygen. This allows for much more in-depth heart rate analysis. For example; it can monitor your VO2 max and adjust your training accordingly.

More generally, the 245 has much more advanced training features and running dynamics for a detailed feedback on your runs.

For people you can’t and don’t want to ever disconnect, the 245 lets you respond to phone calls with text, when paired with your phone.

Contrary to the Forerunner 45, you can track your swimming although, unfortunately, the wrist-based heart rate sensor does not work underwater.

Lastly, a nice small addition to the clock compared to the Forerunner 45 is that it gives you sunrise and sunset.


  • Lightweight
  • On-board music as an option
  • Screen made with Gorilla Glass 3
  • Quick Release Bands
  • Swimming


  • No maps
  • No barometric altimeter and no gyroscope

Who is it for?

Anyone who uses a GPS watch regularly. It is especially great to go on long runs with music, and for people who enjoy detailed tracking of their performances and activities. Serious runners and data addicts, this is the watch for you.

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Garmin Forerunner 645 and Forerunner 645 Music

Garmin Forerunner 645 Music Review
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This watch was released in 2018 and we already did a full review for you back then.
The 645 offers all the same features as the 245, except for Body Battery™, but we’re guessing that this will soon come with a software update.

Just like the 245 music, the 645 music cost $50 extra and can store up to 500 songs.

The stated battery life is up to 7 days in smartwatch mode, up to 14 hours in GPS mode without music, and up to 5 hours in GPS mode with music.

The 645 costs $100 more than the 245, so what do you get for the extra price? It does come with a stainless steel bezel which makes it feel like higher quality. It also supports Garmin Pay. But the real difference is with the extra sensors : it contains a barometric altimeter, a gyroscope and even a thermometer. This is ideal for hikers and runner who wants to track their elevation and their vertical speed. It also means that it supports additional activities such as skiing, snowboarding, stand up paddleboarding and rowing.


  • Still very lightweight
  • Extra sensors for more advanced tracking and more activites


  • No maps
  • Expensive

Who is it for?

So who should buy the 645 over the 245, knowing that it costs $100 more? Any runner or athlete who is serious about tracking their performance and truly cares about having an altimeter and a gyroscope.
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Garmin Forerunner 945

Garmin Forerunner 45 vs 245 vs 645 vs 945
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This top-of-the-line watch supports on-board music, with up to 1000 songs.

It has a record battery life with up to 2 weeks in Smartwatch Mode, up to 36 hours in GPS mode without music, and up to 10 hours in GPS mode with music.

It has much more in-depth activity and fitness tracking. For example, it can estimate heat and altitude acclimatization. It even supports ski and golf in its activity profiles.

Multisport support is actually one of the greatest part of this watch: you can switch between sports / activity with a single button press. This makes it truly ideal for triathletes.

It is the only Forerunner watch that comes preloaded with color maps. It also supports Garmin Pay™ contactless payments.

Note that there is a bundle option for $749.99 where you get 1 extra black band, a HRM-Tri™ monitor and a HRM-Swim™ monitor. In this case the watch band is blue. Otherwise it is black.


  • Every advanced feature you could ever need
  • Build quality
  • Great for triathletes and other multisport athletes


  • Not a mid-range price

Who is it for?

The Forerunner 945 is a true powerhouse aimed at serious runners / athletes who want extensive information and tracking of their training, performance and fitness. It is especially great for people who do more than one activity, such as triathletes. With its extended battery life; it is ideal for endurance runners and triathletes.

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The Bottom Line

The Garmin Forerunner series truly offers a GPS watch for every runner and every budget. Now it’s up to you to decide what sort of activity you do and what you are looking for.

The Forerunner 245 Music is a safe bet for most needs. Although, if budget is your concern and you don’t care too much about all the bells and whistles, we recommend checking out the sale on the older 35 series. It is a great discount on true and tested GPS watches that were among the most popular in 2018. Of course, you would be turning away from on-board music and the latest features.

And don’t forget the Forerunner 645. Although it came out last year and does not have all of the new features (such as Incident Detection or Body Battery), it does support Garmin Pay and has a built-in altimeter and a gyroscope.

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