Garmin has totally revamped its running watch range – and the Forerunner 255 replaces the evergreen 245.
It's a long four years since the Forerunner 245 was launched, and a lot has changed in that time. There will be plenty of runners considering upgrading to the 255, or looking to pick up a deal on a cut-price 245.
Wareable verdict: Garmin Forerunner 255 review | Garmin Forerunner 245 review
Honing in on the key features, here's our take on how the new Garmin Forerunner 255 matches up to its predecessor.
Garmin Forerunner 255 vs 245: Pricing
As is commonly the case, when a new Garmin comes along, the older version drops a little in price. It's no different here with the 255 and 245.
The Forerunner 255 and the 255s is priced at $349/£299. and if you go for the music edition in either of those two options, that pushes the price up to $399/£349.
Switching over to the 245, which is also available in standard and music editions, and the standard 245 is priced at $299.99/£209.99 and $349/£299 for the music version.
So for the base version of the 255 and 245 there's a difference of around $50/£90. For the music editions, it's $50/£50.
Garmin Forerunner 255 vs 245: Design and screen
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Smaller 255s (left) and the standard 245 (right)
The 255 and the 245 share similar sporty designs, with some subtle differences.
The 245 has a 42mm polymer case with 20mm, quick-release bands that weighs in at 38.5g and features a 1.2-inch, 240 x 240 resolution transflective display. There's Gorilla glass 3 on top to boost protection. As a package, it's waterproof up to 50 metres.
The 255 comes in two sizes: 41mm and 46mm, so you can go smaller or larger than the 245.
Both offer polymer cases with 22mm (46mm) and 18mm (41mm) removable straps available.
The larger 255 has a 1.3-inch, 260 x 260 resolution transflective display, Both carry the same 5ATM (up to 50 metres) waterproof rating. weigh ranges from roughly 30-50g depending on the size you go for.
The feeling of these watches on is very similar. They're nice, light comfortable watches to wear 24/7. This is the 255s pictured with the 245 music edition (white case), but both watches don't sit bulky on your wrist and if you like a sports watch small, and light, both offer that.
The decision really boils down to whether you want a smaller running watch, in which case you go for the 255s. The 245 is perfectly fine from a running and general wear point of view. It's got a similar look and screen and the option to switch up that watch band too.
Garmin Forerunner 255 vs 245: Running and sports tracking features
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For pure running features, the 255 and the 245 offer plenty here and if you care about tracking things outside of running, you're well catered here for too.
The 255 has 30+ sports profiles including the core sports of running, cycling and swimming. It now adds in triathlon modes and open water swimming modes, which you don't get on the 245, making the 255 a better fit for triathletes.
Running-wise on the 255, you have the ability to customise data fields, add running power metrics (via a third party sensor) and it's a similar story for added advanced running metrics too. There's navigation features here, letting you upload routes and make use of back to the start and real-time breadcrumb navigation support. That also enables Garmin's PacePro pacing strategies to better prepare and tackle races.
Garmin has also enhanced interval training to include open repeats, extra intervals data and rest screens.
The big difference between the two here though is that the 255 benefits from Garmin's latest multi-band tracking feature to improve outdoor tracking. It does deliver on that front based on our testing, much like it did on the Epix and Fenix 7 series, so if you care about distance tracking accuracy, the 255 will offer big improvements in that department.
The 245 offers similar features minus that multi-band mode, improved interval training mode and additional open water and triathlon modes.
There's Garmin's Elevate heart rate monitor and PulseOx sensor on both watches, with the capacity to pair external heart rate monitors also available. The 255 also includes an altimeter, which you don't get on the 245, letting you measure elevation.
The 255's heart rate tracking in general felt more solid for us compared to the 245, but if you want the best accuracy, it's a case of pairing up that chest strap or armband monitor on both fronts.
If accuracy for tracking runs is a massive priority (and why shouldn't it be?), that's going to be the biggest reason we think to go for the 255 over the 245 here.
Garmin Forerunner 255 vs 245: Training features
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If you're turning to these watches to help you train for an event, or help you pay closer attention to what your data means in terms of recovery and whether you're in a good shape to tackle a speedy marathon, then you're well served here on both watches.
The 245 supports Garmin Coach, to sync training plans over to the watch that adapt based on sessions you manage to complete or miss.
It also offers daily suggested workouts for runners and cyclists and training insights including VO2 Max, training status, training effect, training load and suggested recovery time. Garmin's Body Battery energy monitor is here as well to tell you whether you have good energy levels to tackle your day.
The 255 offers all of those features too, and most notably adds features like acute load insights that compares the intensity of logged workouts to better assess fitness levels.
You've got Garmin's new visual race predictors, which now displays and charts how training impacts on those predicted times. There's a new race widget so once you've added a race into your calendar, it will countdown and offer suggestions on training sessions to complete.
Garmin is also adding a new HRV Status mode, which tracks heart rate variability during sleep to help you better understand your recovery needs and offer another insight into your overall health. That feature needs 3 weeks of data to create a baseline before you can really start to put that data to some use.
If you like to race the all-new Race Day feature is very cool. Major races are officially recognised by Garmin, and the Race Day widget offers a count down, personalized training plans and predicted finishing times.
While the Forerunner 245 doesn't have features like acute load and HRV status along with those new race-centric features, it has the sensor technology on board to deliver it, so they could potentially end up on Garmin's older watch at some point.
If you like the idea of these features and they feel like dealbreakers for you, then it's the 255 you want. Ultimately though, you're getting a good level of training features and insights on both of these watches.
Garmin Forerunner 255 vs 245: Smartwatch and health tracking features
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If you care about smartwatch features on this watches, well, there's very little separating them.
Both work with Android phones and iPhones, giving you roughly the same level of features across the two phone platforms.
You get notifications, which are actionable on Android phones only. There's Garmin Pay and access to Garmin's Connect IQ Store to download apps, watch faces, data fields and widgets and you're getting the same LiveTrack and safety features here on both watches, so friends and family can keep an eye on you when you're training solo.
If you opt for the music editions to grab a music player, you're getting a similar amount of storage (4GB) to play with.
One difference we've noticed that feasibly could make its way to the 245, is the ability to switch between stereo and mono listening modes. That mono mode is there to help extend battery life when streaming music during runs.
If you're planning to stream music during workouts and frustrated by the drop in battery performance on the 245, you should see an improvement on the 255.
On the health and fitness tracking front, both track heart rate, blood oxygen, stress and offer women's health tracking features here too.
The 255 additionally offers Garmin's Health Snapshot feature letting you capture heart rate, respiration, stress, HRV and blood oxygen from a 2-minute reading. They'll track steps and sleep too and we'd say they perform similar across all of those features.
They're good for continuously monitoring heart rate and blood oxygen (at the expense of battery life) while step tracking is solid and motivating and sleep tracking can be good on some days, but still has a tendency to overestimate sleep duration.
Garmin Forerunner 255 vs 245: Battery life
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With every new iteration of a Forerunner, Garmin seeks to improve things in the battery department. Garmin isn't adding solar power or some of the power saving features it's introduced on its pricier Forerunners and top end watches, but it is promising bigger battery numbers with the 255 compared to the 245.
The 255 promises up to 14 days in smartwatch mode, 30 hours GPS battery life, 25 hours in the all-systems GNSS tracking mode and 25 hours when using the new Multi-Band tracking mode.
In contrast, the 245 can go for 7 days in smartwatch mode, 24 hours GPS battery (without music streaming) and 6 hours with GPS and music streaming.
In our testing, the 245 managed to last a week with regular GPS tracking, music streaming and notifications enabled. With the 255, we found you can stretch to over a week if you don't use the Multi-Band tracking, which tends to double the battery life drop-off compared to using just GPS. Adding music streaming into the equation does still put a dent in battery life, though switching to mono streaming can improve things on that front.
Both of these watches are good for a week's worth of training, and the 255 has the capability for going a little longer, if you ditch the Multi-Band.
Garmin Forerunner 255 vs 245: Which one should you buy?
The key thing to take away is that while the Forerunner 255 offers some solid running improvements on the 245, we don't think that you should entirely rule out looking at the 245. Especially when you can find it for a bit less now. So if you've got to pick between the 255 and 245, this is how we see it.
Buy the Garmin Forerunner 255 if... The Forerunner 255 is a big upgrade here, and offers a lot of features for a modest upgrade in the official pricing. For us it's a no-brainer, and one of the best running watches out there.
Buy the Garmin Forerunner 245 if... The 245 is still a proficient training partner and excellent running watch. If you see a sizeable discount, and are looking for a bargain, it still holds up.
How we test
By Michael Sawh
Michael Sawh has been covering the wearable tech industry since the very first Fitbit landed back in 2011. Previously the resident wearable tech expert at Trusted Reviews, he also marshaled the features section of T3.com.
He also regularly contributed to T3 magazine when they needed someone to talk about fitness trackers, running watches, headphones, tablets, and phones.
Michael writes for GQ, Wired, Coach Mag, Metro, MSN, BBC Focus, Stuff, TechRadar and has made several appearances on the BBC Travel Show to talk all things tech.
Michael is a lover of all things sports and fitness-tech related, clocking up over 15 marathons and has put in serious hours in the pool all in the name of testing every fitness wearable going. Expect to see him with a minimum of two wearables at any given time.