Tom’s Guide fitness managing editor Jane McGuire reported a 0.57 km gap between the Garmin Fenix 9 Pro and Apple Watch Ultra 4 in her Frankfurt Marathon: Garmin recorded less.
What the distance readings show
Tom’s Guide published McGuire’s account on October 28, 2026. She reported 42.76 km on the Garmin and 43.33 km on the Apple Watch, and cited 42.19 km (26.2 miles) as the marathon distance.
| Comparison | Garmin Fenix 9 Pro | Apple Watch Ultra 4 |
| Recorded distance | 42.76 km | 43.33 km |
| Distance above the cited 42.19 km course length | 0.57 km | 1.14 km |
McGuire judged the Garmin’s pace data more reliable in urban GPS dead zones during this race. Her verdict was specific to this event.
Rain and crowds shaped the test
McGuire ran in heavy rain and strong gusts on a crowded urban course in Frankfurt. Her account describes 18,000 other runners, buildings that challenged GPS reception, and weaving around participants. She set both watches to kilometers, manually marked laps every 5 km, then downloaded the activity records after finishing.
McGuire also found the Garmin’s physical buttons easier to operate in the downpour. That practical advantage, like her assessment of its pace data, came from this race.
Both watches reported the same average heart rate
The Garmin Fenix 9 Pro and Apple Watch Ultra 4 each reported an average of 172 bpm during the race. McGuire’s Oura Ring 5 reported 179 bpm; she did not wear a chest strap.
In a separate 30-minute run covered by NeoTeo, the watch averages were 160 bpm for Apple and 159 bpm for Garmin, alongside 158 bpm from a chest-worn Frontier X2. NeoTeo’s earlier heart-rate comparison covers that different session.
