The combination of its soft shank and sheepskin interior means that ugg boots are designed for casual, short-term use, and not for situations which require sturdy, protective footwear, as the design emphasis is on style and comfort rather than protecting the feet. Cleaning products should never be applied directly to the sheepskin, as this may cause permanent damage.

While in the boot, the sockless foot is in full contact with the sheepskin lining, thereby maximizing the insulative properties of the boot. The mid-calf shaft, while not encasing the entire lower foot in wool, further enhances the thermal qualities of the boot by encasing the ankle and lower portion of the leg. The wide, rounded toebox, wide shaft, and wide heelbox with a heel-less sole enhance comfort by providing a non-constricting space for the foot.

The durable sole in the classic Ugg measures at the toe about 1/2 inch, at the arch 3/4 inch, and at the heel 1 inch. The thick padding of the sole increases foot comfort during movement, while the soft shank minimizes the weight of the boot.