What size window air conditioner do I need for my room?

As a rough guide, 5,000–6,000 BTU units are marketed for small rooms up to roughly 150–250 sq. ft., 8,000 BTU for mid-size rooms up to about 350 sq. ft., and 12,000–14,000 BTU for large spaces up to roughly 550 sq. ft. The product listings in this roundup state their own square-footage targets; size up modestly for sunny rooms, kitchens, or upper floors.