Whats a long climb and whats a short climb?

I rate a short climb as 500 metres max, although I do not stand usually for 500 metres unless the gradient is relstively easy.

When it is steep (over about 12%) then I can only stand for about 100-150 metres.

A long climb? Well, the longest climb I have had to contend with is about 3.5km, and I did the whole thing seated.

When I have 1km climbs, if I stand at all, it will only be for the final 20-30 metres to help me crest the hill.