Home energy costs are driven by wattage × hours × tariff. Cooling is often the largest summer load, so AC sizing and runtime both matter.
Bill-side estimate
kWh ≈ (Watts × Hours used × Days) ÷ 1,000
Cost ≈ kWh × Rate per kWh (plus fixed charges if your utility applies them)
AC size (rough guidance)
Tonnage relates to cooling capacity versus room area, insulation, sun exposure, and occupancy. Undersized units run endlessly; oversized units short-cycle and dehumidify poorly. Use a structured estimate, then confirm with a technician for unusual rooms (glass walls, kitchens, top floors).
Sketch usage in the Electricity Bill Calculator and room needs in the AC Size Calculator before you buy.