edited January 24
I just ran the NY marathon my Tom Tom recorded 555 metres (over 1500 ft) the channel 7 broadcaster said the elevation was approx 791 ft?
It depends on how it was measured and what digital elevation model was used. If your watch has a barometer it will come up differently than one using GPS. Every product and service also uses a different digital elevation model to verify elevation, so that will also drive different results. Finally, it depends on the thresholds used to measure elevation gain. TomTom uses all gains, regardless of size, while many others only count gains over a certain threshold. Those very small amounts add up over time. Ultimately there is going to be a variance and does 800 feet matter one way or the other, particularly in a road race? A very cursory Google search found at least 5 other different recorded elevations for the race.
I hope this helped answer your question. If so, please mark it as a solution so others can look for it if they have the same question.
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