Some explanation about the definition of "overall ascend"

[routeconverter]

For example, in my hike I do a first ascent of 500 meters positive and after I descend 400 meters and goes up to 500 meters.

Normally the result should be + 1000 meters positive and - 400 meters in negative.

Is it correct ?

Not always. RouteConverter sums up the positive and negative deltas between 2 subsequent positions.