For under-counter installation, single drawer and compact dishwashers are ideal options. The main reason is that they are designed to fit in a predetermined space that would otherwise be used as a single cupboard or drawer space.
Single drawer dishwashers are typically 24 inches deep and wide and have a height of between 16 and 17 inches. Makes and models, available as of February 2015, include Fisher & Paykel models from the DishDrawer series.
Generally, compact dishwashers are around 18 inches wide and 24 inches deep, and have a height of 35 inches. Makes and models available include the Whirlpool WDP350PAAB model and the freestanding GE GSC3500DBB model.