Elevation gain compared


I’m using openrouteservice for all my routing (bike, motorcycle and car). I find it very good and it has all the information needed (at least for me).
Currently I’m in Nice, France and riding some climbs here by bike. I did notice that the elevation gain on some routes differ strongly with the results on my garmin where as others are more or less equal.

I added two screenshot for a route where the evelation gain differed for about 600m. So I don’t know which one is correct but would like to know how this difference is coming about. I do not think that this it is an OSM subject, since Komoot also has an Elevation gain of 1370m for that route and they are using OSM as well.

If needed I can supply the gpx route.


Hi @sake ,

I am surprised that ORS gives larger values than the other systems, because it should rather underestimate the true ascend and descent. Currently, ORS only accounts for the elevation difference between the two ends of a graph edge. For long edges this means that significant variation in elevation may be ignored. This will change in future versions, where edges will be split on elevation differences.

Another source of imprecision might be the satellite data used for building the elevation profile. AFAIK, the currently employed SRTM data has a vertical imprecision of 30m. In particular in mountainous areas this could account for quite some error.

Best regards