EDIT: As mentioned below this is for the most expensive (lowest capacity) tier. I’d been comparing for my own home use and so I would be unlikely to exceed 10TB but if you’re looking at higher capacity then maybe the calculus is different.

For large quantities, it is 3x, and actually less since there are no charges for ingress/egress.

Further questions/comments over email, please, since this is BBs HN thread and I don't want to butt in.