The Apple Watch Ultra 2 has dual-frequency GPS, which receives both the L1 and the L5 satellite signals, and independent tests describe its accuracy as excellent except where dual-frequency is supposed to help most: beside tall buildings and in steep valleys, where signals reflect. The 5K Runner's testing found distance errors of a few hundredths of a mile over a short run, and OutdoorGearLab praised the watch for tracks that follow a trail closely.
The checks in more detail
So a route that drifts on the Ultra 2 is more likely a setting or a start-up issue than a weak receiver. Apple's pages say Location Services must be on, with Motion Calibration and Distance in System Services, and that calibration comes from outdoor walks or runs in open sky at your normal pace. Use the Workout app's outdoor workouts, because indoor types use the accelerometer and not GPS. Wait for the GPS signal before you start, which the Ultra 2 shows in the workout ready screen, and use Precision Start from the Action button.
Wear the watch snug and keep the case clean, since the bezel hosts the antenna. In a dense city, expect more jitter. The Ultra 2's Action button lets you choose Precision Start, which begins the workout with an accurate fix, but you can also pick Backtrack to record a path for the way home on a hike, and Compass Waypoints to mark places. These use the watch's sensors and GPS; if Backtrack does not start, check that Location Services is on and the watch has a fix.
Accuracy improves after a few minutes outdoors, and a first reading indoors is poor. Compare your watch's distance with a known route such as a track or a measured trail to check accuracy, and note that the Ultra 2's accuracy is generally within a small percentage. If the track is consistently off on one route, check the surroundings: buildings, trees and cliffs. If it is off everywhere, calibrate again and restart. Record the comparison to show Apple Support if you need to contact them.
Differential
Likely causes of “Apple Watch Ultra 2 GPS distance or route is inaccurate”, and how to tell them apart
- 1
An indoor workout type chosen
What separates it The route is missing or a straight line
How to confirm Choose Outdoor Run, Walk or Hike
- 2
Starting before the GPS signal locks
What separates it The first minutes are off
How to confirm Wait for the ready state or use Precision Start
- 3
No calibration
What separates it Distance reads high or low
How to confirm Run or walk twenty minutes in open sky at normal pace
- 4
Tall buildings or deep valleys
What separates it The track jitters
How to confirm Expect some error; dual-frequency helps but cannot remove reflections
- 5
Location Services settings off
What separates it No route at all
How to confirm Check Location Services and Motion Calibration on the iPhone
Before you touch a setting
Record this first — changing settings destroys the evidence
- The workout type used
- Where the error appeared on the route
- Whether Motion Calibration and Distance is on
- How long you waited before starting
Try in this order
0 of 6 completedPick an outdoor workout
ReversibleIn the Workout app or with the Action button.
Wait for the GPS signal
ReversibleUntil the screen shows ready.
Use Precision Start
ReversibleFrom the Action button for a fast start.
Check Location Services
ReversibleOn the iPhone: Privacy and Security.
Calibrate outdoors
ReversibleTwenty minutes in open sky.
Wear the watch snug
ReversibleAnd keep the case clean.
Model-specific
What is true of this model and not of its siblings
- Dual-frequency
- Two signals help in difficult terrain.
- Reflections
- City canyons still cause errors.
Stop boundary
When this stops being a self-service repair
- !If GPS never locks in open sky after a restart, contact Apple Support
- !If distance is far off after calibration, ask Apple
- !Check the watch is up to date
Evidence ledger
Sources behind this answer
Outdoor calibration for GPS accuracy.
Fit, Location Services and calibration.
Independent GPS and heart-rate accuracy testing of the Ultra 2.
Hands-on review of the Ultra 2's GPS, battery and controls.
Exact questions
Common questions
Does the Ultra 2 have dual-frequency GPS?+
Yes, L1 and L5.
Why is my route a straight line?+
An indoor type may be chosen.
Where does GPS drift most?+
Beside tall buildings and in valleys.
How do I calibrate?+
Twenty minutes outdoors at normal pace.