Image result for Pelonis 6,000 BTU 115-Volt Window Air Conditioner A 6000 BTU air conditioner is enough for a bedroom in a typical house. An average size bedroom is 219 square feet and a 6000 BTU air conditioner can cool up to 250 square feet. In an apartment, the average size of a bedroom is 132 square feet, so a 6000 BTU air conditioner is more than enough to cool this size room