Built-in dishwashers and stand alone, or portable, dishwashers are about the same size and are typically available in either 18- or 24-inch sizes. Portable dishwashers are sometimes 2 to 3 inches taller because they have wheels.
Built-in and portable dishwashers are available with many of the same options, including stainless steel tubs, multiple wash cycles, heated dry, food disposers and removable silverware baskets. The main disadvantage of a portable dishwasher is that it hooks up to a sink, so the sink may not be used while the dishwasher is operating. An involved initial installation is one of the only drawbacks to a built-in dishwasher.