Here’s our recommendations for the best medium sized models based on Amazon user’s reviews. These portable air conditioners range between 10,000 and 14,000 BTUs of cooling power and are ideal for medium to large rooms from 300 to 450 square feet. These portable ACs are perfect for cooling large bedrooms, living rooms, offices, workshops, and computer server rooms. Most come with convenient features such as auto -evaporation, multiple modes, programmable timers, and remote control operation.