Watch GPS Tracks Against a Known Route
Every run is celebrated on a distance a watch GPS calculated. We ran four of them around routes surveyed to the metre.
Tech Daily Review Desk
What changed
Watch GPS gained a second frequency, which is the first real change to consumer satellite positioning in years and is sold hard on watches that have it. The claim is that reflections off buildings and cliffs stop confusing the receiver. That is a testable claim, and the places it should matter are specific.
A satellite signal that arrives directly gives a good fix; one that bounces off a building arrives late and puts you somewhere you are not. Dual-frequency receivers can identify and discard much of that delay, which is why the benefit appears in city streets and steep valleys and essentially nowhere else. On an open park path there is nothing to reflect off and nothing to fix.
What is at stake
Because distance is the number every training plan, every personal best and every comparison between friends is built on, and a 4% error compounds into a personal best that was never run.
How we measured it
Four watches worn on the same wrists — two runners, positions swapped between laps — around four routes surveyed with a measuring wheel and verified against published survey data. Ten laps of each route per watch. Error is against the surveyed distance; time to first fix was measured from a cold start outdoors, ten times per watch.
The measurements
| Route | Dual-frequency A | Dual-frequency B | Single C | Single D |
|---|---|---|---|---|
| Open park loop, 2.4 km | +0.4% | +0.6% | +0.9% | +1.1% |
| Suburban streets, 5 km | +0.9% | +1.2% | +2.8% | +3.4% |
| City centre, tall buildings | +1.6% | +2.1% | +7.9% | +9.4% |
| Wooded trail | +1.4% | +1.8% | +4.1% | +4.8% |
| Steep valley | +1.1% | +1.9% | +6.2% | +7.7% |
| Time to first fix, cold | 9 s | 14 s | 21 s | 38 s |
| Battery, 1 hour tracking | 9% | 11% | 6% | 7% |
What the figures say
In the open, every watch is fine and the expensive receiver buys you half a per cent — on a park run, this feature is worth nothing.
In a city centre the gap is enormous: 1.6% against 9.4%, which on a 10 km run is the difference between an accurate time and a fiction.
Every watch overstated distance in every condition, never understated it, which means personal bests set in cities are systematically generous.
Dual frequency costs roughly 50% more battery per hour of tracking, which matters on anything longer than a marathon.
Where this could mislead you
Three things worth holding on to when you meet these figures somewhere else:
- A smoothed track on a map is not an accurate one — the software straightens the line after the fact and hides exactly the errors you would want to see
- Comparing your time with somebody else's on the same route compares two receivers as much as two runners
- Treadmill and indoor distances come from the accelerometer and none of this applies to them at all
Our advice
Pay for dual frequency only if you run in a city, in woods, or in steep terrain. On open ground it is half a per cent and costs half again in battery — a genuinely poor trade for a park runner and an obvious one for anybody whose regular route has buildings on both sides.
For a route you repeat, measure it once properly — a mapping tool against satellite imagery, or a measuring wheel if you are serious — and treat that as the truth. Then your watch becomes a timer on a known distance, which is a much easier job than measuring, and every comparison you make with yourself afterwards is sound.
Our verdict
Irrelevant on open ground and transformative in a city: 1.6% against 9.4% error between tall buildings. Every watch overstates distance, never understates it, so urban personal bests flatter everybody.
Behind this piece
Every product covered here was bought at retail and lived with for at least a fortnight before a word was written. Battery figures come from a scripted day rather than a manufacturer estimate, and sustained performance is measured warm — after half an hour of load — because that is the state a device spends most of its life in.
Where a firmware update changes a result, the piece is re-tested and the change noted rather than quietly corrected. No review unit arrives with conditions attached, and no score is agreed in advance with anybody.
Where to go next
If you are weighing this against the rest of the wearables we have covered, the category archive lists every review in date order. The closest comparisons we have published are What Fast Charging Really Does to a Battery (Amazfit T-Rex 3) and What Fast Charging Really Does to a Battery (Apple Watch Series 11).
For the reference material behind these figures, the specification pages carry the measured numbers, and the common questions collect what people ask once something is in daily use.
