Garmin Forerunner 165

What you get, and it is more than the price suggests

The 165 is the cheapest Garmin on this site with an AMOLED display, and it runs the same Garmin Connect platform as the flagships. That platform is the strongest argument for buying any Garmin: the deepest third-party integration in the category, structured workout support, and a training history that transfers if you later upgrade within the brand.

For a first real running watch — someone moving off a phone app or a generic fitness band — it is hard to get wrong. It is light, simple enough that a new runner will actually use all of it, and it does not present a wall of metrics nobody has explained.

The one specification that decides this purchase

The 165 is single-band. That is the entire argument against it, and it is worth understanding rather than glossing.

A satellite broadcasts on more than one frequency. A single-band receiver listens to one. A signal that bounces off a building or wet foliage before reaching you arrives fractionally late — and to a single-band receiver, late is indistinguishable from further away. The reflection gets folded into the position fix, and your track drifts across the road, through buildings, or cuts the corner off a switchback.

A dual-frequency receiver hears the same satellite twice on different frequencies, which are delayed differently by the atmosphere and by reflections. The disagreement between them is a signature it can use to discard the corrupted signal.

The peer-reviewed evidence for how much this matters is the 2020 eight-watch study, which measured 3.2-6.1% overall distance error but only 0.9-4.1% on an open track, with urban and forest conditions substantially worse. Every watch in that study was single-frequency. So the study describes what a receiver like this one does, and cannot tell you how much a modern multi-band watch improves on it, because nobody has published that comparison.

Practical translation. If you run on open roads, tracks and parks, single-band positioning is already performing near its ceiling and the 165 costs you nothing. If your complaint is a track that wanders between buildings or under tree cover, this is the specification that causes it, and this watch is the wrong fix.

Test before you upgrade, for free

Before assuming you need multi-band, find a 400 m running track and run exactly four laps in lane one — 1,600 m, one of the few precisely measured distances most people can reach.

• Under 1% off: your receiver is working properly.
• 1-3% off: normal, and consistent with the published literature.
• Over 3% off on a track: check your satellite mode is not set to power saving and that you waited for a full lock. A watch upgrade will not fix a settings problem.

Then run your usual problem route. If the track is accurate and the trail is not, you have confirmed the diagnosis and the 165 is not the watch. If both are bad, buying any new watch is premature.

The evidence position

No independent validation of this model exists that we could find — not of its optical heart rate, not of its positioning. It sits at manufacturer specification on our hierarchy, the same tier as most of the range.

There is one Garmin measurement worth carrying, because it is unusual for any consumer watch to have been measured at all. The 2025 Sensors placement study tested a wrist-worn Forerunner 55 against a Polar H10 reference and recorded a bias of roughly 33 bpm during burpees, the largest error in the paper. Wrist devices in the same study showed limits of agreement of about ±10-19 bpm during a cycling warm-up.

That is a different, older watch, so it is not evidence about the 165. What it is evidence about is wrist optical sensing during rapid intensity change, which applies to every watch on this site including the ones costing five times as much. If interval heart rate is why you are shopping, the fix is a strap, and it costs less than the difference between watch tiers.

Where it sits against the alternatives

Against the COROS PACE 4: the PACE 4 has dual-frequency reception and 41 stated GPS hours at a comparable price, which on specification is simply more watch. What Garmin has that COROS does not is the ecosystem, and for a lot of runners that is the deciding factor rather than a footnote.

Against the Forerunner 55: the 55 is cheaper, and Garmin states 14 smartwatch days and 20 GPS hours for it. It is also the specific device caught at roughly 33 bpm of error during burpees in the placement study. The 165 buys you an AMOLED screen and a more current platform.

Against the Forerunner 570: the 570 adds multi-band reception and a wider metric set for meaningfully more money. If the track test above showed a problem, that gap is what closes it.

What we could not verify

• Optical heart-rate accuracy. No published measurement of this model.
• Positioning accuracy. No published measurement of this model.
• Battery figures.Garmin's, under Garmin's conditions, and published less granularly for this model than for the Instinct 3.
• Sleep staging.Garmin's sleep algorithms have no independent polysomnography validation we could find, at any price point.

Who should not buy it

Anyone whose GPS track wanders.Single-band is the hardware that causes that. This is the clearest don't-buy case on the page.

Anyone racing very long. This is the entry tier, and battery is a hardware problem — check the stated figure for the mode you will actually run before committing to an ultra with it.

Anyone buying it to fix heart-rate data. Same wrist optical class as everything else. Buy a strap instead.