How to Choose the Right AC Size for Your Space

One of the most common mistakes in AC installation is choosing a unit based on room size alone rather than a proper load calculation. An oversized unit cools the room quickly but shuts off before it can remove enough humidity, leaving the space feeling clammy, while also cycling on and off frequently, which increases wear and shortens lifespan. An undersized unit runs constantly and still struggles to reach the set temperature, driving up energy costs without delivering comfort. A proper load calculation accounts for room dimensions, ceiling height, insulation quality, window orientation and glazing, number of occupants, and heat-generating appliances in the space. This is typically expressed in BTUs (British Thermal Units) per hour. For example, a well-insulated 20-square-meter bedroom might need roughly 8,000 to 9,000 BTUs, while a sun-facing living room of the same size could need more. Commercial spaces add further variables like occupancy density and equipment load. Rather than estimating, it's worth having a technician perform a proper calculation — the right-sized system costs less to run and lasts longer.