Garmin Forerunner 255 review: runner’s best friend gets GPS and multisport upgrade

Greater accuracy, longer battery and full support for triathlons makes the best running watch even better

Garmin’s latest running watch has been upgraded in almost every way, bringing multisport tracking, more advanced GPS and a bunch of high-end features down to a more affordable price with the Forerunner 255.

The longstanding series is available in two sizes for the first time with the 255 – a small 41mm-wide case and a larger 46mm model, which means it should fit comfortably on a wider range of runners’ wrists. But it has very big shoes to fill, replacing the well-regarded Forerunner 245 from 2019.

Both sizes of watch have the same RRP. It is £300 ($350/A$629) for the standard model or £350 ($400/A$699) for a version capable of storing and playing music to Bluetooth headphones from Spotify and others without the need for a phone.

A selection of watch faces available on the Forerunner 255.
There are plenty of pre-loaded watch faces available, each customisable by colour and data displayed, plus many more third-party options in the Garmin IQ Store. Photograph: Samuel Gibbs/The Guardian

The new watch has a sleeker design, more like 2020’s Forerunner 745 than the Forerunner 245. The sharper colour transflective LCD display is super clear in daylight with a backlight for night-time use but it doesn’t have a touchscreen, instead relying on five buttons for navigating the interface, which work well for exercise, even in adverse weather.

The watch is snappier than its predecessor, too, making syncing and switching between data screens, activities and watch faces much faster. The watch is thin enough to fit under shirt cuffs while being light and very comfortable to wear all day and night for weeks without charge.

The Forerunner 255 pictured on a male wrist.
The high-quality 22mm silicone strap has plenty of adjustment but can be swapped out for any standard third-party one. Photograph: Samuel Gibbs/The Guardian


  • Screen: 1.1 or 1.3in transflective MIP LCD

  • Case size: 41 or 46mm

  • Case thickness: 12.4 or 12.9mm

  • Band size: standard 18 or 22mm quick release

  • Weight: 39 or 49g

  • Storage: 4GB

  • Water resistance: 50 metres (5ATM)

  • Sensors: GNSS (Multiband GPS, Glonass, Galileo, BeiDuo, QZSS), compass, thermometer, heart rate, pulse Ox

  • Connectivity: Bluetooth, ANT+, wifi

Longer battery life

The Garmin Connect app on an iPhone showing settings for the Forerunner 255.
The Garmin Connect app on an Android or iPhone handles settings, syncs data and watch updates via Bluetooth. Photograph: Samuel Gibbs/The Guardian

The 255 can be used independently of a phone but works best paired with an Android or iPhone via Bluetooth, which enables the syncing of your data to Garmin Connect and various smartwatch features such as call or message notifications.

Alternatively, you can sync via USB cable to a PC or Mac or via wifi straight to the cloud on music-supporting models.

The battery life is great. The 46mm version lasts about 14 days as a smartwatch with notifications, general heath tracking, including sleep, and more than three hours of activity tracking. That’s double the life of the Forerunner 245.

The watch will last a good 16 hours of running with the most accurate location tracking mode active or up to seven hours while also listening to music. Switch to the more efficient GPS-only mode and it will last up to 30 hours of tracking. The smaller version lasts slightly less but both models can handle a marathon or even two depending on how fast you are.

The new watch supports Garmin Pay, which is useful if you need to buy a drink or unexpectedly get the bus home while on a run, but few mainstream banks are supported in the UK.


The back of the Forerunner 255 showing the sensor cluster and the charging port.
The sensor cluster sits in a lump against your wrist next to the charging port. Photograph: Samuel Gibbs/The Guardian

The Forerunner 255 is generally repairable. The battery is rated to last at least a few years of frequent charge cycles while maintaining at least 80% capacity. The watch does not contain any recycled materials. Garmin guarantees at least two years of security updates from release but typically supports its devices far longer. It offers trade-in schemes for some lines and complies with WEEE and other local electronics recycling laws.

Running and multisport

Some of the data screens available during a run shown on the Forerunner 255.
Each activity can be customised with various options for data screens, GPS modes, heart rate and other features, so you can track and see what you need during and after your workout or race. Photograph: Samuel Gibbs/The Guardian

The 255 builds on the excellent sport tracking capability of its predecessor, adding lots of new features and capabilities inherited from Garmin’s more expensive models. It has the firm’s new 4th-gen heart rate sensor, a barometer and compass, and the next-generation “multiband GPS”. This increases tracking accuracy and reliability around tall buildings or vegetation by locking on to newer frequencies from GPS satellites.

It has plenty of useful features without being overloaded with gimmicks. The watch consistently gets a GPS lock within seconds – much faster than its predecessor – and produces more accurate live pace estimations when running. It records practically every metric you can think of allowing you to track or train by a wide variety of different methods including heart rate zones and power, although you’ll need a compatible foot pod or chest strap for running power (sold separately for a range of prices). It has the stamina feature introduced with the high-end Fenix 7, too, which is a useful live estimate of how much energy your body has left during a run.

The other big upgrade is multisport tracking, such as for triathlons, a feature previously reserved for Garmin’s top models. It will track more than 30 different activities, including a collection of workouts across strength and cardio, multiple forms of cycling and swimming, and can combine them into one seamless event.

Garmin has also beefed up its automated coaching system – free – which can now create a fully structured and adaptive training plan for races, including the buildup and tapering to help you perform your best on the day. It is currently designed for running, not cycling or multisport, but it is very impressive – few companies offer this level of personalised training plan, let alone one that adapts in real time to your progress.

Health monitoring

The Forerunner 255 wishing the wearer a good morning before showing the morning report.
A new morning report greets you at the start of the day, giving you a summary of your sleep, heart rate variability and other bits. Photograph: Samuel Gibbs/The Guardian

The 255 has a solid set of general health-tracking features, too. Automatic sleep tracking feeds into Garmin’s excellent body battery, which makes it easy to understand the impact of sleep, activity and rest on your day.

It has stress tracking, all day heartbeat monitoring , the standard calories, steps, stairs and sedentary alerts, blood oxygen tracking and other metrics. Plus Vo2 Max fitness measurement, a standard cardiac measurement, and a tool estimating your recovery time after exercise. Overnight heart rate variability is a new metric, which takes three weeks to calibrate to your baseline and can then can be used to highlight over training, stress, illness and other factors.


The Garmin Forerunner 255 comes in two sizes (41mm or 46mm) and costs £299.99 ($349.99/A$629) or £349.99 ($399.99/A$699) with offline music playback.

For comparison, the Forerunner 55 costs £149.99, the Instinct 2 costs £299.99, the Forerunner 955 costs £479.99, the Fenix 7 costs £599.99. The Coros Pace 2 costs £180 and the Polar Vantage V2 costs £343.20.


The new Forerunner 255 takes everything that was good about its excellent predecessor and turns it up to 11.

The faster interface, longer 14-day battery life and option of different sizes for a better fit are very welcome. It is thin, light and comfortable to wear. It ticks almost every box for general health tracking, handles basic smartwatch functions and the top model supports offline music from Spotify and others.

Garmin’s Connect app is the best in the business and provides easy syncing to Strava and other popular services. And the watch tracks almost every metric you can think of making it easy to see what is important for your training plan.

The next-gen GPS upgrade and addition of true multisport tracking for triathlons and other events brings useful high-end features to a more palatable price. The new automatic race coach looks like it will be extremely useful tool, too.

The only thing missing is onboard maps for route guidance if you get lost, which is still the reserve of more expensive models.

The Forerunner 255 isn’t the cheapest on the market but it is the best. If you don’t need offline maps and routing, this running and multisport Garmin should be at the top of your list.

Pros: slim, light, real buttons, clear screen, choice of sizes, multiband GPS, accurate heart rate, extensive stats, multisport, comprehensive health tracking, highly customisable, long battery life, optional offline music, basic smartwatch features.

Cons: expensive, no touchscreen, screen fairly basic compared with smartwatches, no offline maps.

An email alert on the Forerunner 255.
Smartphone notifications are basic but enough to alert you something has happened. You can fire off basic replies to messages on Android but not an iPhone. Photograph: Samuel Gibbs/The Guardian

Other reviews


Samuel Gibbs Consumer technology editor

The GuardianTramp

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