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Garmin Forerunner 255S review

Garmin's new Forerunner 255 is the cheapest true multisport watch the brand offers. But is it worth its £300 price tag?

Our rating 
4.2 out of 5 star rating 4.2

The multisport market is flush with options, and yet more continually come to market. Garmin alone has dozens of watches for you to choose from and that choice has expanded with the recently launched Forerunner 255.


Announced at the same time as the Forerunner 955, the 255 is the next evolution of the popular Forerunner 245, though the latter will still be available.

While the 245 was a great watch, it lacked the multisport functionality that triathletes need, so it was music to our ears when we heard the 255 was going to correct that.

As with most Garmin watches, the 255 is available in a range of iterations. A smaller size, on test here, comes with a 41mm case size, while a larger option sports a 46mm case. Both options have a retail price of £299.99.

Then there’s a choice of whether or not you want music storage. If you do, you’ll get space for up to 500 songs that can be downloaded from the likes of Spotify or Amazon Music and listened to via Bluetooth headphones, meaning you can run and listen to music without having to take a phone. The damage? An extra £50.

While it won’t leave a gaping hole in your bank balance in the same way as the Garmin Fenix 7 or the Forerunner 955, £300 is still a pretty large chunk of money. So is it worth it?

Garmin Forerunner 255S review

Activity tracking

To answer that question, let’s start with arguably one of the most important updates for triathletes: the addition of a multisport mode. This allows you to record brick training sessions or a full race in one go.

As with other Garmin watches sporting this functionality, it’s pretty intuitive to do, with a click to start. The lap button is then used to mark your entry and exit from both T1 and T2. Testing it at a sprint triathlon in the Midlands, we found it easy to use and generally accurate, though the open-water swim tracking was off marginally.

While recording each leg, you have access to data including time, total time, speed/pace, distance, heart rate and lap time and distance.

Other available activity profiles include much of what you’d expect, including running (indoor, track, trail etc), cycling (indoor, outdoor, MTB etc), pool and open-water swimming, cardio, strength, hiking and so on. We won’t list them all here, as there are other 30.

When starting up an activity we found GPS connection a quick and painless affair and accuracy is as good as we’ve come to expect from Garmin. The 255 has multi-band GNSS support, which is what you’ll also find on the 955 and the Fenix 7, so it’s impressive to see it on a watch that’s half the price.

Using multi-band mode does cut battery life though, which drops from 20 hours (standard GPS) to 13 on the 255S when in use.

Training features

As it costs considerably less money you’d think that the 255S will ship with less fancy training features. You’d be right, of course, but what’s left is still pretty impressive.

Among the features you’ll find suggested workouts, running power metrics (you’ll need a running power pod for this) and a race predictor that uses your running history to predict your run times.

Most useful for triathletes (aside from the activity tracking), though, is likely to be the heart rate variability (HRV) feature. This measures the freshness or fatigue of your neural system and will attempt to inform you how ready to train you are. A bad score and you may want to rest up, while a good score means you’re ready to perform.

It takes a while to gather enough data to be useful, but we found it a pretty good match to how we were feeling most of the time. We wouldn’t rely on it entirely, but teamed up with feel and our own experience, it proved a handy aid during a tough training block.

Wrist-based heart rate tracking is never 100% accurate, but the 255 gave a good account of itself, largely following many other Garmin devices with its performance.

Training Status, Training Effect, Performance Condition, Acute Load and Recovery Time are other features we found useful, if not taken completely as gospel. If you’ve got your max heart rate set up properly you’ll find Training Effect’s analysis handy, as it tells you the aerobic and anaerobic affect of your training.

Acute Load helps you understand if you’re taking on too much training load too soon, while Training Status helps to provide a holistic view of your recent training and its effect on your body and fitness.

What you don’t have here are some of the newer features spotted on more expensive watches, such as built-in maps, Training Readiness and Real-Time Stamina.

Display and interface

As we’ve come to expect from a Garmin watch, the home display is fully customisable and, even on the smaller size, is legible in a range of lighting conditions. The colours on the screen are vibrant and the backlight does a fine job of helping provide clarity in low-light situations.

Anyone that’s previously owned a Garmin will be familiar with the five-button interface, which we find incredibly intuitive when you know it.

From the homepage you can toggle through different data screens, while a click will take you into a more detailed field of data that you can scroll through. Moving through different screens was a speedy experience with almost zero lag on show.

Battery life

Garmin says the Forerunner 255S is capable of up to 12 days (14 days for the standard 255) battery life in smartwatch mode and up to 26 hours (30 hours for the standard 255) in GPS-only mode. That’s plenty to see you through a full Ironman or a week of heavy training. Of course, if you listen to music that will come down somewhat.

There’s no solar charging here like you get with the Forerunner 955 or Fenix 7, but honestly, we found the battery life to be more than sufficient and were easily getting more than a week out of it with multiple training sessions.

Garmin Forerunner 255 verdict

Given the rising prices of multisport watches, we were momentarily tempted to call this an entry-level watch for those on a budget. But then we remembered it’ll set you back £300. Admittedly, that’s a fair chunk of money, but the 255 does sit toward the lower end of Garmin’s multisport range.

The addition of multisport tracking makes it a winner over the slightly cheaper and older Forerunner 245, while the range of features is impressive. But you are paying for them.

It’s also £180 cheaper than the new Forerunner 955. If you’re not bothered about missing out on built-in maps and a few top-end features, we’d suggest saving your money, as the 255 does what most triathletes will need it to.

Our 255S was barely noticeable on the wrist and weighs just 39g, so it’s a great alternative to bulkier options. It’s a pleasure to use and looks great, too.

Our only criticism is that it just feels a little overpriced. If Garmin knocked £50 off, we’d be much happier.

In a line: Great features in a small package, but cheaper, comparable options on the market from other brands.

Score: 84%

Also consider…

Coros Pace 2

If you’re not too worried about sporting a Garmin-branded watch on your wrist, you may be tempted by the Coros Pace 2. With an RRP of £179.99 it comes in at a considerably cheaper price but still offers a fantastic range of features.

It offers up to 30 hours in full GPS mode, offers training plans, multisport tracking, plus accurate GPS and heart rate components. You get all the usual metrics you’d expect for swim, bike and run, while the Coros app offers a great interface for consuming all of your data.


In our review last year, we concluded it was “Coros’ best yet and a staggering watch for under £200”.