Built-in GPS means the watch has its own satellite receiver and can record your route with the phone left at home. Connected GPS means the watch borrows your phone's location, so the phone has to come with you. Some trackers switch between the two on their own. Which one you need depends on whether you run, ride or hike without your phone, how much battery you can spare, and where you train.
How each one works
Google's Fitbit help pages describe the three options clearly. Phone (connected) GPS uses the GPS sensors in your phone and needs the phone within about 30 feet, roughly 9 m, of the tracker; that distance is Google's figure for its own Fitbit and Pixel Watch devices. Built-in GPS uses the tracker's own sensors to log route, pace and distance, and can drain the tracker's battery faster, so Google suggests charging to at least 80 percent first. Dynamic GPS picks the best source at the start of a workout and may switch during it.
Apple Watch makes a similar choice behind the scenes. Apple says older models use the iPhone's GPS when it is available to save battery, while Series 8 and later, SE (2nd generation) and Ultra models use their built-in GPS even with the iPhone nearby.
| Built-in GPS | Connected GPS | Dynamic GPS | |
|---|---|---|---|
| Phone needed during the workout | No | Yes, close by | Optional |
| Watch battery during GPS workouts | Drains faster | Spared; the phone does the work | Depends on the source in use |
| Accuracy depends on | The watch's receiver |