AC Size Calculator
Find the right kW capacity for your room. Enter your details below for a personalised recommendation.
Room Dimensions
Enter the approximate dimensions of the room you want to cool and heat.
Room area: 20.0 m²
How to Calculate Air Conditioner Size
Choosing the right size air conditioner is one of the most important decisions when buying a new system. A unit that is too small will struggle to cool your room, while one that is too large will waste energy and create an uncomfortable environment.
The basic formula is straightforward: multiply your room's floor area (length x width in metres) by 125-150 watts to get the approximate cooling capacity needed in watts. Divide by 1,000 to convert to kilowatts (kW).
Factors That Affect Sizing
- Room insulation: Well-insulated rooms need less cooling capacity. Poorly insulated rooms (e.g. old homes, no ceiling insulation) may need 20-30% more.
- Windows: Large north or west-facing windows increase heat gain significantly. Add 10-20% for heavy sun exposure.
- Climate zone: Darwin and Cairns need more cooling capacity than Melbourne or Hobart for the same room size.
- Ceiling height: Standard 2.4m ceilings are accounted for in the base calculation. Add 10-15% for each additional 30cm of ceiling height.
- Room usage: Kitchens generate more heat. Rooms with many occupants need extra capacity.
For a precise recommendation, use our calculator above or contact our team for expert advice.