How to determine the right air conditioner size

When dealing with Melbourne’s unpredictable daily weather changes, it’s important to choose the right air conditioner size. First, do you need a split-system, portable, or window air conditioner? And once you determine that, how do you know what size you’ll need?

The air conditioner size doesn’t refer to the unit’s physical dimensions. It refers to the cooling and heating capacity when measured in Kilowatts (kW). To get the best bang for your buck, you’ll have to get an accurate sized capacity in order to cool down your space.

So, don’t go running for the largest air conditioner you can find. Bigger doesn’t always mean better. Because choosing the right size will keep running costs low and maximize performance.

Calculating Capacity Size

To find the right air conditioner size, you’ll need to measure the room in square metres. Multiply the length by the width of the desired room. This number will give you the area of the room in squared metres.

You will also need to consider the ceiling height. Spaces with high ceilings will need more energy to cool and heat.

Factors that Affect Air Conditioner Efficiency

Every home is different especially when it comes to location, size, and build. To calculate the perfect air conditioner size, you’ll need to pay attention to these factors. Following these guidelines will ensure that the capacity meets your needs.

Are your ceilings and walls insulated? Homes that are well insulated won’t need as much cooling and heating.

Where is your home located? A house in Melbourne will have different cooling and heating needs than a home in Sydney.

Does your room have a lot of windows? Having blistering sun rays pouring into your room could require a larger air conditioner cooling capacity. If you get a lot of shade, this may mean you’ll need a larger capacity for heating. 

Air Conditioner Room Size Calculator

Below you will find our rough air conditioner room size calculator. This can help you determine which capacity will be needed for a particular room.

Room Size Example Approx. Capacity
Up to 20m² Small bedrooms, kitchens 2-2.5 kW
20–40m² Bedrooms with en suites 2.5-5 kW
40–60m² Large bedrooms, kitchens 4-6 kW
60+m² Open areas, living rooms 5-9kW


Remember that these are rough estimates, and it would be best for you to reach out to a professional to get exact measurements.

split system

Avoid These Common Mistakes

We know it can be tempting to buy a large air conditioner that will keep your house cool and warm or to buy a smaller air conditioner to mitigate costs. But, it’s best to buy the right air conditioner size. Because it will save you money and maximize the unit’s performance.

Oversized air conditioners don’t run for long because they meet the space’s cooling and heating needs fast. Once the unit meets the needs, they turn off and stop running, which means the air conditioner isn’t dehumidifying the home. This on-and-off process brings on wear and tear faster and causes the unit to break down.

Buying a smaller unit may mean that it will work at maximum effort to cool and heat the space. This means an increase in power and in wear and tear.

This is why it’s best to buy the right sized air conditioner. Properly sized air conditioners will run longer, dehumidify the air, and last longer.

To get more insider information on air conditioners, heaters, and special offers, make sure to subscribe to our mailing list! Need help determining which air conditioner is right for your home?  Contact the experts and visit their website to find out more.


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