Only guessing based on the shape and thickness, but probably not real well--meaning you might get them to stack 2-high, but unlikely to be very stable after 3-high.
RayFThey’re stable when stacked, but don’t nest far into one another. In my cupboard, I stack 2 of the largest, 3 of the medium, and 5 of the smallest. I’ve had one set for almost 15 years while my kids were young and accident prone and they’ve held up. They’re amazing glasses.