Garmin Forerunner 45 vs. 55: Which Should You Pick?

The Forerunner 45S in white and the Forerunner 55 in aqua side-by-side in my hand

The Forerunner 45 and 55 are the latest versions of Garmin’s entry-level model. The Forerunner 45 was released in April 2019, and just two years later, the line was refreshed with Forerunner 55 in June 2021. If you’re deciding which watch to buy, or whether to upgrade, here are some clear-cut reasons to choose one over the other. 

For context, I’m a marathoner, former triathlon-dabbler, and GPS watch nerd. Over the past few years, I’ve tested 11 GPS watches by borrowing from friends or getting loaners. I tested my friend’s FR45S, and I bought the FR55 secondhand for my mom. I do a lot of GPS watch comparisons, so if you’re deciding between other models, take a look at those (and follow my Strava to see what I’m currently testing)!

Also note that this post contains affiliate links, meaning that I may earn a small commission at no extra cost to you, if you purchase through those links. This income allows me to keep writing these reviews, and I appreciate your support!

Things in Common: Forerunner 45 and 55

Before we dive into the reasons to choose one watch over the other, here are some things they have in common.

Features in Common

Tracking profiles for popular activities: running indoors/outdoors, biking indoors/outdoors, cardio, elliptical training, stair stepping, and yoga. You can also program interval workouts to follow from your watch.

Everyday fitness and health stats: steps, heart rate, stress, sleep.

“Fancier” training stats: VO2 max (aerobic performance capacity), Body Battery (energy levels based on heart rate variability, stress, and activity).

Basic smartwatch features: weather, calendar, messages, find your phone, Smart Lock (automatically unlock your phone when watch is in range).

Safety features: LiveTrack—allows your friends and family to follow your activity in real time; Incident Detection—alerts your emergency contacts with your location if an incident is detected (you must be connected to your phone, though)

Drawbacks in Common

No touchscreen: while touchscreens can be seen as both a good or bad thing, neither the Forerunner 45 or 55 has one. Their button navigation is easy to use, however.

No barometric altimeter: you won’t be able to track floors climbed throughout the day, and your elevation stats will be less accurate during workouts. If you’re running mostly on flat roads, or don’t need to know your real-time elevation, this probably won’t be a huge issue though, especially since you can correct elevation data in Strava after the fact.

No music: you’ll still have to carry your phone if you want to listen to music. For your watch to carry music, you’ll have to go the next tier up to the FR245.

No pulse ox: if you need to keep an eye on your blood oxygen saturation, neither the FR45 or 55 have this function (but again, the FR245 does)

No open water swimming: these watches won’t work for triathletes. Of the current-generation Garmins, only the FR255 and up have this tracking profile. I recommend the COROS PACE 2 if you need open water swimming on a lower budget.

If both these watches still sound like a good fit to you, here’s how to decide which one is to buy.

Reasons to Choose the Forerunner 55

Forerunner 55 on its side
the Forerunner 55 lying flat

The Forerunner 55 is basically a “lite” version of the Forerunner 245, a mid-tier favorite. The FR55 got a makeover to even look more like the FR245. The FR45 has a thinner watch band that curves and doesn’t lie flat. Now, the FR55 and FR245 both have the flexible quick-release watch band and look nearly identical, other than the slightly smaller display size of the FR55.

The Forerunner 55 is also the first entry-level Garmin to have Pool Swimming. I’ve personally found Garmin’s swim tracking somewhat inaccurate (10-15% more), but I’m also not the strongest swimmer. Others have said that they track quite accurately.

As for other activities, the FR55 tracks HIIT and Pilates while the FR45 doesn’t. It also has a special Track Running (for more accurate tracking) and Virtual Running mode.

For those who want to keep a closer eye on their menstrual cycle, there is menstrual tracking on the watch itself (instead of being limited to the Garmin app for the FR45).

If you don’t want to charge your watch often, the FR55 has longer battery life. It gets up to 2 weeks on smartwatch mode and 20 hours using GPS, while the FR45 gets 7 days on smartwatch mode and 13 hours on GPS.

Finally, the Forerunner 55 also has more advanced training metrics, including:

  • Recovery Time: amount of time to rest before a hard workout
  • Race Predictor: estimated finish times for 5k, 10k, half marathon, and marathon
  • PacePro: helps you create and customize a pacing plan for runs and races
  • Suggested workouts: training recommendations to improve your fitness

Reasons to Choose the Forerunner 45

The Forerunner 45S in white on my wrist
garmin forerunner 45s
back of forerunner 45s

Because the Forerunner 55 is the more updated watch, the FR45 does have fewer features. Both watches retail for the same price, so if you’re going to pay retail, the new version is much better value.

That said, you can find the Forerunner 45 for much cheaper now. Many third-party retailers are selling it for $130, and it’s also easily found secondhand for $100 or less. If you don’t need the extra features of the FR55, then the FR45 can be a better deal.

If you have really small wrists, you might also want to opt for the Forerunner 45S (pictured in these photos). The FR45 came in two case sizes (the display was the same size between the FR45 and 45S, but the casing was different). The Forerunner 45s is quite light at 32g, while the FR45 weighs 36g and the FR55 weighs 37g. All watches are relatively light and suitable for small wrists (I speak from experience!), but if you don’t want to notice your watch, you might prefer the FR45S.

The Bottom Line

Garmin’s entry-level Forerunner series no longer feels that basic with the updated Forerunner 55. If you want pool swim tracking, more training tools/metrics, and nearly twice the battery life, the FR55 is your watch.

But, if you don’t need all those features and want to save some money, the FR45 is a great option, especially if you’re looking for something lighter on the wrists.

If you already have the FR45 and are wondering whether you should upgrade, it’s probably not worth it unless you specifically need the new features (better for your wallet and the planet). The FR45 isn’t really that old and has all the basics. If you do need to upgrade though, you might consider the FR245, which can be found for almost the same price as the FR55 and has more features (see my comparison of the FR55 vs 245 for more info).

Where to Buy the Forerunner 45 and 55

If this review helped you, it would mean a ton if you purchased through my affiliate links. I also want to encourage you to buy secondhand or from small, local running stores if you can. I don’t get paid if you do that, so if you still want to show your appreciation financially, you’re welcome to buy me a virtual coffee.


Forerunner 45
Forerunner 55


Forerunner 45
Forerunner 55

Other retailers

Swappa (used electronics)

I hope this helped you make a decision! Feel free to leave any questions in the comments, and happy running.

You may also like these posts:

Forerunner 55 vs. 255
Forerunner 55 vs. 245
Forerunner 45 vs. 245

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  1. I was lead to your site while comparing Garmin watches. I really enjoyed reading your travel experiences, specifically your language immersion. Your blog completely hit the spot! Thanks for sharing your life experiences.

  2. Hi Lily,

    Thank you for the comparison. I would like to point out an engineering issue with the FR45. Because of how they made the band attachment to the watch, my FR45 watch has become detached from the band. The soft plastic screw hole attachments wore out and now the watch is unwearable and unfixable. You can also see that on the FR55 they changed how the band attaches to the watch to relieve this issue and essentially, go back to how all watches are attached to their band. This issue is a big enough of a problem for me to say go with the FR55 since they switched the band and it can no longer break on the user.

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