Garmin Forerunner 170 vs Garmin fenix 9 51 mm: which should you buy?
Both are Garmin training watches, but they sit a long way apart. The Forerunner 170 at £259.99 covers running and everyday fitness. The fenix 9 at £999.99 adds a 51 mm sapphire case, 100 m water resistance and weeks of battery for serious outdoor use. Most runners will not need the fenix.
Pick the Forerunner 170 if
You mostly run or go to the gym, you want Garmin's training features, and a lighter watch at a quarter of the price makes more sense.
Pick the fenix 9 51 mm if
You spend long days outdoors, you want the toughest build and the longest battery Garmin offers, and a 51 mm case suits your wrist.
How do they compare side by side?
| Spec | Forerunner 170 | fenix 9 51 mm |
|---|---|---|
| Brand | Garmin | Garmin |
| Reference | 010-03920-50 | 010-04763-11 |
| Case diameter | 42.6 mm | 51 mm |
| Thickness | 11.9 mm (better) | 14.7 mm |
| Water resistance | 50 m | 100 m (better) |
| Movement | Smart | Smart |
| Crystal | Chemically strengthened glass | Sapphire crystal |
| Strap | Silicone, 20 mm quick release | Silicone, 26 mm QuickFit |
| Colourway | Black case, black and amp yellow strap | Carbon Grey DLC titanium bezel, black band |
| Launched | May 2026 | August 2026 |
| Brand RRP | £259.99 (better) | £999.99 |
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A dot marks the better spec, where "better" is clear-cut (more water resistance, longer power reserve, a harder crystal). Specs from each brand's published information.
Read the first looks: Garmin Forerunner 170 · Garmin fenix 9 51 mm
Questions people ask
Is the fenix 9 too big for a small wrist?
The 51 mm version is large. On a wrist under about 16.5 cm the Forerunner 170 at 42.6 mm will sit much more comfortably.
Do both work with an iPhone?
Yes. Garmin watches pair with both iPhone and Android through the Garmin Connect app.