Garmin Forerunner 170 review

I haven't worn the Forerunner 170. This review is my reading of what other people measured, checked on 3 November 2026, and it asks one narrow question: is this a good watch to carry through a plan for your first race?

I think so, with two catches. Heart rate holds on steady runs and loosens in hard sessions. And the GPS is single-band, which matters mostly if your race runs between tall buildings.

£259.99 on garmin.com (UK), checked 3 November 2026.

Everything below from outlets is independent, non-peer-reviewed field testing, usually one person on one route. I found no peer-reviewed study of this model.

What the plan side gives you

The5krunner lists Garmin Coach adaptive plans on the watch, plus Daily Suggested Workouts and a Quick Workout Generator. That covers what a first-timer needs: a session for today, sent to the wrist. One open question: TechRadar's Forerunner 570 review says adaptive training plans moved to the paid Connect+ tier, and I couldn't confirm how that lands on the 170. Check what's free before you count on it.

It isn't all aimed at beginners. The5krunner says Training Status "is not intended for the occasional or beginner runner", though it adds that a beginner can use the watch perfectly well. T3 says custom workouts cap at an hour, and that Garmin's algorithm often avoids giving you long runs. For a marathon plan that's a real complaint, because the long run is the session you can't skip.

Tom's Guide found the quick workouts hard enough that its reviewer scaled them back. The Run Testers said much the same, which is no surprise: Tom's Guide's reviewer founded The Run Testers, so I count those two outlets as one voice.

Nobody I read tested whether a Garmin Coach plan actually gets a new runner to the start line in better shape. That part is unverified.

If you only want the basics, The5krunner points first-time buyers to the Forerunner 70. I've set that argument out in Forerunner 70 vs 170.

GPS away from tall buildings

The5krunner's numbers are the most useful I found.

That's +40 m in the canyon, but don't lean on it. The5krunner calls results there "somewhat of a lottery", says closeness to the footpod means little because errors cancelled out, and suggests a footpod for pace work in built-up areas.

The Run Testers reported tracks matching multi-band watches on their routes. Mountaineer Journey, a one-person blog, saw road distances within 1 to 2% and blamed single-band for errors under tree cover.

These don't quite agree. My guess is that route explains most of it. Multi-band helps in some places, though solid independent figures on how much are thin, as I explain in multi-band GPS explained.

Heart rate: steady yes, hard less so

The5krunner compared the watch with a Forerunner 970 and HRM 600 chest strap.

On a steady parkrun: -0.1 bpm bias, limits of agreement -2.6 to +2.5 bpm, 1,737 samples. In short intervals: +0.5 bpm bias, limits -7.8 to +8.7 bpm, 1,297 samples. The average barely moves. The spread triples.

One warning on that review. Some Forerunner 170 files were lost on sync, so a few sessions used a Forerunner 70 instead. I've ignored those here, since it's a different watch.

Tom's Guide saw the watch lag a chest strap in an interval session, in warm weather, when optical sensors tend to do better. Mountaineer Journey logged 150 bpm against 154 bpm on a Polar H10 over a 25-minute treadmill run, and scored accuracy at 7 out of 10.

For easy runs and long runs I'd trust it. For intervals I'd add a strap, and here's how to connect one to your watch.

A tracker isn't a medical device. These readings are estimates for general fitness, and if you have symptoms or concerns, talk to a clinician.

The race predictor

I found no test of the 170's VO2max estimate or race predictor. None.

The closest is a 2026 peer-reviewed study of a different watch, the Forerunner 265, in 20 people. I read the abstract only and didn't check its funding. It found race predictions fast: 129.97 min against 137.55 min for a half marathon. That result doesn't carry over to the 170. It's simply my reason for not setting a goal time from a predictor alone.

Battery on race day

Garmin claims 20 h, GPS only and 14 h with all systems on. The5krunner's two burn tests came out at 20.83 h and 16.67 h, though it couldn't say which satellite mode was active. T3 lost 25% on a three-and-a-half-hour walk on all systems, which works out at 14 h.

Any of those covers 42.2 km (26.2 mi) at any pace you're likely to run. Daily charging is the weaker side: The Run Testers charged every 3.5 days or so with the screen always on.

Who I'd point at it

A runner following a first 10 km, half or marathon plan, who wants guidance on the wrist and races on open roads. For the wider field, see my first-marathon list or the marathon goal page.

Triathletes should skip it. DC Rainmaker notes there's no multisport mode.