To cool a bigger or busier room ranging from 250 to 350 square feet, you’ll want to step up to a midsized air conditioner rated at 7,000 to 8,500 Btu. If it’s for a bedroom, heed our noise scores.

For example, a small room, 100-150 square feet, would require 5,000 Btu/hour, while a 1,000-square-foot room would demand 21,000 Btu/hour.

Next, multiply the square footage of your room by 20. If your space is 300 square feet, you want to find a model capable of producing at least 6,000 BTUs. As a guide, consider 5,000-BTU models for ...

As another example, to cool a two-room apartment (living room and bedroom) of 800 sq/ft, you would need a 16000 BTU air conditioner. For a large family house of 12000 sq/ft, a 24000 BTU system ...