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Garmin Forerunner 255 First-Look Review

Now a full triathlon watch, the Forerunner 255 also offers improved GPS accuracy and a morning report to guide your training each day

Garmin Forerunner 255S
(Image: © Nick Harris-Fry / Future)

The Garmin Forerunner 245 has been a fixture in our best running watches round-up since it was launched, offering all the key features runners at any level needed to track and analyse their training.

Garmin is now targeting triathletes as well as runners with the new Forerunner 255, which offers a multisport mode for the first time in this line of devices. That’s just one of a host of updates to the watch, which I have had to test for a couple of days ahead of the launch.

Garmin Forerunner 255: Price And Availability

The Forerunner 255 is available now from Garmin US (opens in new tab) and Garmin UK (opens in new tab), and comes in two sizes: the standard 255 which has a 46mm case and the 255S which has a 41mm case. There are two versions of each size – the 255 Music and 255S Music both offer music and cost $399.99 in the US and £349.99 in the UK, while the base 255 and 255S models don’t have music and cost $349.99/£299.99. That’s a significant price rise from the Garmin Forerunner 245, which now costs $224.99/£209.99 for the base model and $349.99/£299.99 for the 245 Music.

Garmin Forerunner 255S

Garmin Forerunner 255S (Image credit: Nick Harris-Fry/Future)

What’s New?

Along with the new sizes and multisport support, the Forerunner 255 adds the multi-band GPS tracking that Garmin introduced to its range on the Fenix 7 and Epix 2 watches early in 2022. In my long-term testing of the Epix 2 I have seen an improvement in the GPS accuracy of the watch compared with other devices, so it’s good to see this rolled out to cheaper watches in Garmin’s range.

The Forerunner 255 also offers Garmin’s morning report feature, which provides information like your sleep rating and weather forecast, along with your suggested workout for the day and your heart rate variability (HRV) status. The latter is also a new feature on the watch and the info it provides can be used to judge what kind of training you do that day because it shows how recovered your body is. 

Garmin has also improved the training analysis on the watch by adding acute load tracking, which looks at the intensity of recent workouts to see if the load is appropriate for you. You also get an indication of what your training focus has been – easy, tempo or anaerobic – something that has been available on Garmin’s more expensive watches for a while but isn’t on the Forerunner 245.

Some of that training analysis also feeds into the new race widget. Once you set up a race in this (using Garmin Connect) it will give you weather forecasts for the event and a predicted time, and your suggested workouts will adjust in line with the race you have planned. There is also a countdown timer for the race in the widget, to give you a little bolt of adrenaline each time you come across it.

Garmin Forerunner 245 and Garmin Forerunner 255S

Garmin Forerunner 245, left, and Garmin Forerunner 255S, right (Image credit: Nick Harris-Fry/Future)

If you use a Garmin Running Dynamics Pod or HRM-Pro you will be able to see your running power on the Forerunner 255 live during your runs without using an app, and the watch also now has Garmin Pay contactless payments.

The Forerunner 245 had a 42.3mm case, so the new sizes come in slightly smaller in the case of the 41mm Forerunner 255S, and a fair bit larger with the 46mm Forerunner 255. The 255 has a 33mm 260x260 pixel screen, while the 255S’s is 27.9mm 218x218 pixel. The Forerunner 245 has a 30.4mm 240x240 pixel display.

Other than the different sizes, the 255 and 255S have the same features, but the larger watch offers more battery life, lasting up to 14 days in smartwatch mode and 30 hours with GPS-only sports tracking (using multi-band GPS or listening to music will reduce this). In comparison the Forerunner 255S lasts up to 12 days in smartwatch mode and 26 hours in GPS-only tracking mode. The Forerunner 245 lasts up to seven days in smartwatch mode and offers 24 hours of GPS tracking.

Unlike the Forerunner 245, the new watches have a barometric altimeter, which makes for more accurate elevation tracking on the run and allows you to track floors climbed as part of your everyday activity stats.

Garmin Forerunner 255S

Garmin Forerunner 255S (Image credit: Nick Harris-Fry/Future)

Key Features

The new features on the 255 build on the strong sports tracking and training analysis the Forerunner 245 offered. The watch also offers breadcrumb navigation and you can sync routes across from both Strava and Komoot, and the music support on the 255 Music includes the ability to link a Spotify Premium account to store your playlists on the watch offline.

Along with the daily suggested workouts you can set up training plans for 5K, 10K and half marathon events to follow on the watch, and the training status information it provides will tell you if your training is productive in terms of making you fitter.

Health and activity tracking features include blood oxygen saturation tracking and Garmin’s Body Battery feature, which gives a snapshot rating of your energy levels out of 100 throughout the day. The Forerunner 255 also supports Garmin’s women-focused features, including pregnancy and menstrual cycle tracking. This information feeds into the new race widget so training can be adjusted around your menstrual cycle.

First-Look Review

I have been testing the Garmin Forerunner 255S for a couple of days ahead of the launch and have run twice with it to get an idea of the accuracy of the multi-band GPS tracking and heart rate sensor. Unfortunately I wasn’t able to link the watch to Garmin Connect so it didn’t have my training history and I didn’t have time to log enough data to activate the training analysis and HRV status features.

On the run the watch did impress, producing very accurate GPS tracks. On the second run I compared it directly with the Forerunner 245 and the GPS track from the new watch was clearly an improvement at certain points, tracking me on the right side of the road and not cutting corners like the 245 did at points. The overall distance and pace was similar from the two watches. but those who prize the most accurate GPS possible will notice the improvement from the multi-band tracking.

Garmin Forerunner 255S

Garmin Forerunner 255S (Image credit: Nick Harris-Fry/Future)

The Forerunner 255S also logged my heart rate accurately on the run, mostly staying within a few beats of the reading from a chest strap. During some strides at the end of my run it did lag behind the spikes in my heart rate on the short sprints, but for the most part it was accurate enough to use to pace my runs, even if I would link a chest strap myself to get the best data possible into the training analysis (you can connect external sensors via both ANT+ and Bluetooth).

I tracked one night of sleep with the 255S and also got an HRV graph for the night, and it was slightly concerning that the results were very different from the measurements of an Oura Ring, which I consider the most accurate sleep tracker I’ve tested. It’s early days so I will reserve judgement, but for the new HRV status and improved training analysis to be genuinely useful it will need accurate data.

Overall, the updates to the Forerunner 255 and 255S are useful and for a very keen runner like myself I would be happy to pay the extra to get this one ahead of the Forerunner 245 for the increased GPS accuracy in particular. 

However, I am probably in the minority, and my initial impression is that most runners will still be more than satisfied with the features and accuracy of the Forerunner 245 and 245 Music – and getting the basic 245 for $225/£210 is a significant saving. 

That said, having two size options is useful, and triathletes will naturally be delighted by the new sports modes on the Forerunner 255. Other features like Garmin Pay, running power and the increased training analysis might be key to some people as well. 

Nick Harris-Fry is a journalist who has been covering health and fitness since 2015. Nick is an avid runner, covering 70-110km a week, which gives him ample opportunity to test a wide range of running shoes and running gear. He is also the chief tester for fitness trackers and running watches, treadmills and exercise bikes, and workout headphones.