- Great analytics
- Race Day countdowns
- Superb HR accuracy
- No Training Readiness
The breadth of Garmin’s running watch range can feel bewildering, but the Garmin Forerunner 255 is the company’s biggest crowdpleaser.
Priced in the mid-range, the Forerunner 255 is packed with running features, metrics, and analysis – and replaces the enduringly popular Forerunner 245 that was launched in 2019.
But is it the best running watch for you? We’ve spent a month clocking up serious miles with the Forerunner 255 to bring you our ultimate verdict.
Price and comparison
The Forerunner 255 and 255s have been given a price hike over its predecessor. The Forerunner 255 costs $349/£299 price tag for non-music versions and $399/£349 with music storage capabilities.
The cost, in our mind, is the biggest issue. We’d say that most people will be best served by the standard non-music version, but it’s still a big outlay, and it’s not even the most advanced running watch in Garmin’s line-up.
The biggest change in design from the Forerunner 245 is the introduction of the smaller 255S. That means the Forerunner 255 is now available in 46mm and 41mm sizes – making it better suited to thinner wrists.
The design is certainly functional, and it’s no looker. The plastic construction doesn’t impart the same allure as the Fenix 7S, for example. However, it’s tough, and more than adept at getting sweaty.
We found it incredibly comfortable to wear, even to sleep, with the strap secured by a strong buckle.
Garmin’s familiar five-button navigation system is in play here. It will be second nature to anyone that’s used Garmin watches in the past, but there’s a learning curve for newbies. And the Forerunner 255 is loaded with features that can take a bit of finding.
Running and training features
On the surface, the Forerunner 255 is an evolutionary change from the 245.
First up, there’s a lot more to the Forerunner 255 than just running. It’s loaded with workout modes, including triathlon, and sessions can now be combined if you swap disciplines.
Garmin’s swim tracking is some of the best in the business, and Garmin brings its stroke detection, SWOLF scores, and metrics here.
The mainstay of the Forerunner 255 is run tracking, and there are also trail, treadmill, and track workouts too.
You get a few screens of data, with live time/pace/distance, split time/pace/distance, and heart rate all easily cycled through on the watch.
The screen is super-easy to read and data is legible, and like most Forerunners and Fenix devices, it’s a great running partner.
But most of what you get while out on a run is available on the Forerunner 55 – it’s after your run that things get interesting.
The advanced training metrics of VO2 Max, Training Load, and Training Effect are all carried over from the 245 – and that puts this sports watch in the top category of Garmin watches for analysis.
VO2 Max analysis guides most of the data from the watch, including race predictions, which are much-improved thanks to recent updates. Our finishing times for 5K and 10K distances were pretty much in the ballpark, and in line with races.
The Forerunner 255 will also track running power – if you connect it to a Running Dynamics Pod or HRM-Pro chest strap.
But now the Forerunner 255 takes that further with the new Race Day feature.
If you have a race booked in, there’s a countdown widget that will show how long you have to train, your predicted finish time, progress towards your target time, and probable weather conditions for the day.
Garmin uses the same tech as its PacePro feature (also found on the 255) which analyses the course and elevation of known race routes from its database, to help guide you to a finish time.
And this stuff is unique to Garmin – and it’s a set of features that runners will love. For those that enjoy training for races, it’s a great addition – and well implemented (although a bit of a process to set up).
It will also tailor your Garmin Suggested Workouts to your primary event too.
Garmin Suggested Workouts
Garmin will suggest workouts for you before every run, which if you just want to head out the door and run are awkward to navigate and annoying to dismiss. It’s slightly presumptuous to assume that users will be interested in the recommended workout every time they start a session – but maybe that’s just us.
The recommended workouts are based on your training load, current aims, and fitness. We found the basic suggestions to be good in theory – although the suggested pace was usually way too slow.
The workout suggestions and pace targets did improve dramatically once we targeted a race with a specific finishing time using the Race Day feature. This introduced much more intense interval sessions as well as recovery runs.
However, we suspect many people will simply choose to turn this off.
A new feature to the Forerunner 255 – has filtered down from the Garmin Lily and seems to be available across the range.
It shows a snapshot of data from your morning, including last night’s sleep, HRV status, and today’s recommended workout.
It’s shown when Garmin thinks you’re up and awake, takes a few seconds to scroll through, and dismiss, and we love it.
It brings good data to the fore in a way that rivals (Whoop and Oura) can only do via the smartphone app. We found it non-intrusive, friendly, and insightful. It’s a great addition, albeit one we believe will be found on most Garmin watches going forwards.
One of the biggest additions to the Forerunner 255 is Garmin’s HRV Status – a feature that apes the likes of Whoop, Oura, and Fitbit.
HRV – or heart rate variability – is a metric that examines the time between heartbeats. Stress and fatigue can lower HRV, and studying it can help you ascertain when is the right time to train.
First off, it takes around three weeks of wearing the 255 to sleep to get an HRV baseline. We found early readings to be substantially lower than our Whoop 4.0 – but as the calibration period elapsed, we found similar HRV readings across the two devices.
Once the baseline is established, Garmin’s HRV Status color-codes your HRV average reading from the past week and shows whether you need to lay off training, or you’re fit to take the strain.
Oddly, the previous night’s HRV is presented as a raw figure in milliseconds, but without context – and arguably we feel this number is more important than the weekly average that’s shown. HRV can bounce around quite a lot, based on how you slept or alcohol consumed, so we’re more interested in the current score than a weekly average.
On the Forerunner 955, the current HRV number is contextualized as part of the Training Readiness Score, but that feature has not been released for the 255.
We’d argue that Garmin has been a little mean by not releasing the more useful Training Readiness Score for the 255.
But HRV Status does offer most of the same information, just in a less user-friendly way. It’s a great addition to the Forerunner 255 and fills a big gap in Garmin’s analysis of recovery. But like many aspects of health tracking in the Garmin ecosystem, it’s not very user-friendly and requires interpretation by users.
Heart rate accuracy
We put the Forerunner 255’s Elevate optical heart rate sensor up to Garmin’s HRM-Pro chest strap.
The result, over a long, steady run with plenty of elevation, was an excellent performance – and one of the best running watches, we’ve tested.
Over a 10K run, we found the Forerunner 255 to match the chest strap for average HR (156 bpm) and max HR (189 bpm). Many optical sensors will stumble when reaching maximum HR levels, so it’s a bit positive to see these levels accurately recorded.
Of course, if you start to test the sensor with rapid hill sprints or repeats, you will start to get bad data. But this is where we’d advise using a chest strap, which the Forerunner 255 reports.
As more running data and analysis is based on heart rate, it’s important to get decent accuracy from the optical sensor –and we certainly found that here.
Like the Fenix 7, Epix, and Forerunner 955, the 255 gets GNSS support for more accurate GPS tracking.
It’s a big feature and a reason to buy the Forerunner 255, and ensuring the best accuracy and pacing data is something all runners can benefit from.
All systems' GNSS tracking isn’t turned on by default, so you will need to head to the Navigation menu on the watch to sort that. It does impact battery life, but unless you’re busting out ultra distances then we’d say the trade-off is worth it.
We still found slight wandering in built-up areas, but the All Systems tracking does offer noticeably better accuracy – especially when you’re near trees and buildings. In open areas, it was almost spot on.
Except for the HRV Status, there’s the full array of Garmin’s now ubiquitous health tracking features.
The sleep tracking is good, although we do feel it tends to overestimate sleep when compared to the likes of Whoop and Fitbit, which we tested against.
We did feel accuracy was better here, and that poor sleep was noted with low scores – and that a good night’s rest earned us scores of 90+ (out of 100) – where previously there have been clear issues with deep sleep detection.
We’d say Garmin’s sleep tracking isn’t world-class, but it’s much-improved and worthy of being included in the mix of recovery data.
The Stress Tracking and Body Battery features are still here – but as we’ve often criticized, the data doesn’t feel interesting or useful. Both could do with an overhaul.
There’s a SpO2 sensor on board, but again the data from this, including nightly respiration rate is quite buried. And nighttime blood oxygen saturation is turned off by default to save battery. Again, Garmin doesn’t make much of this data, and you have to go out of your way to find it.
Notifications are a strong part of the Garmin ecosystem, and it’s more of the same here.
Any notification heading to your phone can be pinged to your wrist. There are some minor elements of control, but it does lack granular control. That means that if you want WhatsApp messages to ping your watch, you’ll also have to have notifications from your smart indoor cameras or other nonsense on your phone.
There’s also quite a mechanical vibrate that isn’t that subtle – and we could hear it buzzing away downstairs when we weren’t wearing it. We turned off notifications altogether pretty quickly.
NFC is on board, so Garmin Pay is supported for wrist-based payments.
And then there’s the Music conundrum. Like the Forerunner 245, there is a Music version that supports MP3s, and offline playlists from the likes of Spotify, Amazon Music, and Deezer.
This will be of serious interest to those determined to leave their phone behind on runs – and for others, is a good way to save $100 on the price of the watch. We’d probably choose to save money and opt for the non-Music version, as we’ve never been very organized about having the tunes we want to be synced.
Despite the chunky price tag, the Forerunner 255 is a mid-range device in Garmin’s array of sports watches – and so is its battery life.
We got about 11-12 days out of the device, with an average of 3-4 runs a week.
An hour of running shaved off around 3-4% with All Systems GPS turned on, which checks out with Garmin’s battery life estimates.
We’d say that on balance that’s decent battery life – although it’s far from the best out there. If you compare it to a Fenix, Enduro, or Forerunner 955 it’s on the low side, but many people looking at the Forerunner 255 could (and should) be considering the Apple Watch. And that, excuse the pun, is comparing apples to oranges in terms of battery life.
How we test