Both portable air conditioners and window units can do a good job of cooling a small apartment, but Consumer Search recommends portables because they can be moved easily from one room to another to provide cooling as needed. Portables typically cost $300 to $500, as of 2015.
Portable air conditioners come in small and large sizes. The small ones deliver less than 10,000 British thermal units of cooling power and are suitable for cooling areas up to about 325 square feet, while the large ones can cool 400 square feet or more. The size needed depends on the room's size and how much sun it receives. Consumer Search recommends dual-hose models as more efficient than single-hose models.