How old is Toshiro Hitsugaya in human years and in soul society years?

Answer 1

Toshiro's age is rather indeterminate. Rukia goes and says that she is ten times Ichigo's age, and he is fifteen to sixteen years old. That means she is roughly one hundred fifty to sixty years old.

Toshiro states nothing about his age, except that he doesn't like being called things like child, kid or elementary school student. However, that doesn't mean that he isn't a kid age wise, but means that he doesn't like being treated like a kid.

As for his physical age, he is height wise shorter then Ichigo's sisters by roughly one to three inches. However, there is the slight chance that he is small for his age. He is likely at the least, equivalently ten years old, while at the most thirteen, which might be pushing it.

One might think that Toshiro is thus one-hundred to one-hundred and thirty years old overall, however, there is one small factor one has to take into consideration, when he died. Rukia died as an infant, so she is easy. However, it is not at all clear when Toshiro died, how old he was. What we do know is that he is part of the plot line forty years ago, which means he is at least forty to fifty years old.

So... 50 to 130 is a good guess at his age.