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What size split system air conditioner do I need?

Unit of Measurement

Your first step in determining what size air conditioning unit to purchase for your room/s should be to understand what unit of measurement is used. Within Australia, the output of an air conditioner is measured in kilowatts (kW).


Why it is important to select the correct size

The short answer to this is, to ensure your air conditioner runs efficiently and effectively. Careful consideration must be taken regarding the conditions the unit will be running in and a bigger unit is not necessary better. Air conditioners are designed to run in cycles, if the AC is too big and is cooling the room too quickly it will mean the unit isn't allowing itself enough time to complete the cycle it is designed to do. It will cool the room, allow time for the room to heat up again and then switch back on in a never ending cycle, which doesn't prove to be efficient from a unit use perspective or energy use perspective. 

If the AC is too small you may find that it is in constant overdrive as it attempts to cool or heat the room. Working to this capacity will mean that the unit will require more energy ($$$'s for you) or could affect the longevity of the product. 


How to know what size split system air conditioner to buy?

Room Size (m² Cooling Capacity
10 2.1 kW
15 2.5 kW
20 3.25 kW
25 3.5 kW
30 4.0 kW
40 5.0 kW
50 6.0 kW
60 7.5 kW
70 9.0 kW


*Please note that this table is a guide only and that many other factors may impact the recommended size such as;
  • high ceilings
  • rooms which contain a lot of sunlight
  • rooms with a lot of windows
  • rooms with many appliances running (eg. computers, servers etc)
  • ceiling insulation rating