As of March 2015, Lowes.com offers countertop convection microwaves with capacities of 1.1, 1.2 and 1.5 cubic feet. The power levels of these microwaves range from 900 to 1200 watts. Several brands are available, including Sharp, KitchenAid, GE, Cuisinart and Frigidaire.
Size is an important consideration when purchasing a microwave, according to Good Housekeeping. A family typically needs a microwave with a minimum 1.2 cubic foot capacity, because this is enough space for large casserole dishes. However, considering the appliance's intended use is also valuable. A small microwave that has a 0.5 cubic foot capacity is large enough to heat soup and beverages.