Out of curiosity, what is the height difference between the living area and the bedroom area? Is that also equal to the height of the storage area below the bedroom?
It's going to vary as most have said above. But it is also going to be around 2 feet difference. Which means at least 3 steps. Standard risers are 8" max. If it's more than 2 feet you'll see 4 steps. I don't think I've ever been in one with 4 steps, but they probably exist.
The height of the storage area is going to be less than that, because the structure that makes up the bedroom floor is going to use about 4" of it.