Picking between the Forerunner 255 and the trusty Forerunner 245 is a difficult task, with both proving to be top Garmin watches in our extensive testing.
In typical Garmin fashion, the differences between these two generations are relatively small, despite three years falling between their release. And, as we often see when the company's solid old-gen models are updated, there are actually plenty of reasons to stick with the old instead of opting for the new.
In this guide, we'll be covering all the key areas of both these running watches, as well as highlighting where the new-gen model has the upper hand. By the end of it, you'll have a better idea of whether the Forerunner 245 or Forerunner 255 is the better pick for your needs.
Perhaps the most significant portion of this comparison is the price - and the Forerunner 245, as you would expect, is a significant chunk cheaper than the newer 255.
Though various deals typically may see it offered for even less, the rough price of the standard old-gen model currently sits around $199 / £149. That's superb value.
You'll pay slightly more for the 245 Music model, but, even still, it works out much less than the starting price for the 255S (41mm) and 255 (46mm), which is $349 / £299 and $399 / £349, respectively.
Unless you can find a good deal on a Forerunner 255 model, the current pricing makes the older 245 a much more attractive option. Even with the upgrades that we'll discuss below, it makes it very difficult for the 255 to justify such a big disparity.
At first glance, there are very few design differences you can actually spot between these two - perhaps a testament to the feedback Garmin received between generations.
There are some changes, though. The big one is the addition of that aforementioned 41mm 'S' model, which keeps a case option present to those with smaller wrists, while the standard 255 model bumps things up to 46mm - a much better fit for those with medium and large wrists. The 245, on the other hand, is only available in a 42mm case.
Control is the same throughout all versions of the watch, however, with five buttons on the case's edge. It's just a color MIP display with no touchscreen capabilities on both, too, though there is a slight bump in resolution in the 255 compared to the 245. It's not massively noticeable, but the 255 is a bit sharper and more vibrant when placed side-by-side with the older model.
All in all, the look isn't drastically different here. And, generally, we're a fan - neither of these models offers the allure of something like a Fenix 7, but they're both light and comfortable options that blend into day-to-day wear nicely.
Heart rate tracking and GPS
While the pure cosmetics of these devices don't differ significantly, there are some design changes that have a sizeable effect on the sports tracking experience.
Present on the 255 devices is the updated version of Garmin's Elevate optical heart rate sensor, while, internally, they also boast a compass, barometric altimeter and support for multi-band GPS. While there's not a game-changing difference between the pair's heart rate accuracy, we would still say the 255 offers a noticeable improvement in this regard - and you can read our reviews for the in-depth breakdowns here.
Arguably, an even bigger upgrade is the ability to play around with more GPS modes, such as 'All Systems' (hitting up GPS, GLONASS and Galileo satellites concurrently), which isn't an option on the 245. Enabling one of these modes does mean battery life takes a bit more of a hit, but the fact you're able to get more accurate readings on the 255 (particularly for those occasions when your workout takes you through built-up areas or woodlands, say) will no doubt be a huge plus for some.
Software and sports tracking
The remaining differences are really software-based ones. The 255 is able to show race prediction times for 5K, 10K, half marathon and marathon distances that are slightly different (and a bit more accurate) from the 245's predictions, while there's also a race calendar that helps tailor workout suggestions around an upcoming event you've entered.
The multi-sport mode, something that isn't present on the 245, also makes it a much better fit for triathletes. We'd say the 245 is more strictly a watch for runners, as a result.
A feature we really enjoy using - HRV Status - is only available on the 255, as well, giving you a good reference point in how your body is adapting to the current training load by showing how this is trending over the previous week.
Even when coupled with the heart rate and GPS upgrades, we're still not totally convinced the software changes are significant enough to sway the overall tie for most people. The 245 still offers the vast majority of the same features, after all.
However, when you also consider that the 255 will continue to receive even more software benefits, and the 245 likely won't, it does become easier to separate these two.
This is always a difficult area to assess, given the number of variables at play, but, based on our testing, it's clear there is a pretty big difference between these two generations.
Whereas the battery life in GPS mode is only marginally improved, we'd say, we did manage to get several days more out of both the 255S and standard 255 when compared to the 245.
No variation of the device is particularly poor in this regard, but the Forerunner 245's rough baseline of around 7-9 days is noticeably less than the 11-12 days we'd get from the 255, for example.
Still, as we say, there's more opportunity for battery drain with the 255, given the various GPS tracking options at your disposal.
It's all about how you use the device, but we'd suggest power users - ones who are going to be tapping into the likes of GPS tracking every day - should probably favor the 255 series.
Verdict: Which is best?
We believe this one, more than in an average comparison, really comes down to how much you're willing to spend.
The differences between the two generations are relatively sizeable if you're looking to track more than just running, but the core experience is largely available on the older Forerunner 245 - and, depending on where you shop, for half the price.
Both are excellent mid-range watches, and it goes without saying that the Forerunner 255 is a more complete device - offering better battery life, more accurate tracking and improved design options.
If you're new to both of these devices, we'd say it's just about worth plumping for the Forerunner 255 - especially if you can find it a little cheaper than the RRP.
Should you upgrade?
If you already own the Forerunner 245, things are a little more complicated.
While we'd often recommend those looking for an upgrade to consider a more advanced Forerunner model, something like the Forerunner 955 doesn't necessarily offer the best bang for your buck when compared to the 255.
So, once again, if there's a particular upgrade or feature you'd be fond of that isn't present on your current Forerunner 245 - or you can the device it at a discounted rate - it's probably worth pulling the trigger.
How we test