usual density of native hair is around 80g/cm2
how much you can get with a transplant depends on the thickness of your hair, e.g if your hair is very thick its much harder to implant a lot of them alltogether compared to thin hair but in this case you also get increased coverage with fewer hair , I guess top doctors would be able to get a density around 50-55 safely with 1 procedure and around 70 with a touchup, always depending on hair thickness.