What Size Air Conditioner Do I Need? A Perth Room Guide

The rough rule

As a starting point, allow about 0.15 kW of cooling per square metre of living space. So a 30 square-metre lounge needs roughly a 4.5 to 5 kW unit. Bedrooms need less; rooms with lots of west-facing glass or high ceilings need more.

What changes the number

• Ceiling height — more air to cool
• Sun exposure and west-facing windows
• Insulation and how the room is used (kitchen vs bedroom)
• Open-plan areas that flow into other rooms

Do not just round up

An oversized unit short-cycles: it blasts cold, switches off, and leaves the room humid while wearing itself out. The right size runs steadily and efficiently. That is why we size to the room, not the catalogue.

Use the calculator

Our aircon size calculator does the maths and matches you to a real unit at a real Perth price. For whole homes or open-plan spaces, ducted or several splits usually beat one big head — and we confirm the exact size on site for free.

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Browse split systems or get a quote.