The size of a dehumidifier is usually determined by the amount of moisture it extracts from the air in a 24-hour period. The Association of Home Appliance Manufacturers' guidelines are a good resource in deciding on a correctly sized dehumidifier. Portability is also important, especially for dehumidifiers that will be used in multiple rooms. Ideally, the unit should be lightweight, compact and have rolling casters or carrying handles.

A built-in humidistat is a good feature to have because it...