Various embodiments concern a handheld beverage container. The beverage container includes a vacuum chamber located radially between an inner tubular sidewall and an outer tubular sidewall and axially between an inner bottom wall and an outer bottom wall. The combined heat capacity of both of the inner tubular sidewall and the inner bottom wall can be greater than the combined heat capacity of both of the outer tubular sidewall and the outer bottom wall such that a vacuum insulated thermal reserve is formed. Heat can be exchanged between the thermal reserve and the beverage to stabilize the temperature of the beverage to counteract ambient cooling/heating of the beverage. Various embodiments concern a cap that seals with a disposable cup that is held within a container body, allowing a beverage to be contained in the disposable cup while being insulated by the container body, with or without a thermal reserve.

An insulated cup holder includes outer and inner walls separated by an empty volume, and a gap between a cup and the inner walls. A silicone ring at the top of the inner wall seals and holds the cup, and the inner walls are tapered to contact a base of the cup to seat the cup in the cup holder above an inner shell base, and the only contact between the inner shell and the cup walls is at the cup base.