The Australian summer can often be a scorching affair (especially in Brisbane!), with hot and humid days making it difficult to stay comfortable at home or work. We’d argue that an air conditioner is almost essential for every Australian household or workplace; however, when it comes to buying an air conditioner, one of the most important considerations is the size. In this blog post, we will guide you through the process of choosing the right size of air conditioner for your space.

Why Is the Size of an Air Conditioner Important?

Choosing the right size of air conditioner is crucial for several reasons. First and foremost, having the right size will ensure optimal cooling and energy efficiency. An undersized air conditioner will struggle to cool your space, resulting in higher energy consumption and a shorter lifespan. On the other hand, an oversized air conditioner will lead to frequent on-off cycles, causing unnecessary wear and tear on the unit and resulting in higher energy bills.

Factors to Consider When Choosing an Air Conditioner Size

Before buying an air conditioner, consider the following factors to determine the appropriate size for your space:

1. The Size of Your Space

The size of your space is the most important factor in determining the size of your air conditioner. Generally, the larger the space, the bigger the air conditioner you will need. However, other factors, such as ceiling height, insulation, and the number of windows and doors, also affect the cooling capacity required.

2. The Climate of Your Region

The climate of your region plays a significant role in determining the appropriate air conditioner size. In Australia, the climate can range from mild to extremely hot and humid, and this will affect the cooling needs of your space. For instance, if you live in a hot and humid region like Brisbane, you will need a larger air conditioner with higher cooling capacity to combat the heat.

3. The Level of Insulation in Your Space

Insulation can significantly impact the cooling needs of a space. Poor insulation allows heat to enter your space, making your air conditioner work harder to cool it. Thus, having proper insulation in your space can help reduce the size of the air conditioner needed.

4. The Number of Occupants in Your Space

The number of people in a space can also affect the size of the air conditioner needed. More occupants mean more body heat and moisture, making the space harder to cool. If you have a large family or host frequent gatherings, consider opting for a larger air conditioner to handle the extra heat load.

Choosing the Right Size Air Conditioner for Different Spaces


For a bedroom, a small-sized air conditioner with a capacity of 2.5 kW to 5 kW is suitable. This size is ideal for cooling medium-sized spaces such as bedrooms and can be easily wall-mounted or installed on a window.

Living Rooms

The living room tends to be the largest space in a house and thus requires a larger air conditioner. A unit with a cooling capacity of 7 kW to 10 kW is sufficient for most living rooms. However, if you have a larger or open-plan living room, a unit with a capacity of up to 14 kW may be required.


Offices, especially those with several employees, require proper cooling to ensure a comfortable working environment. A split system with a cooling capacity of 10 kW to 14 kW is suitable for most office spaces.


Choosing the right size air conditioner is crucial for maximum comfort and energy efficiency. At Just-In Time Electrical, we are experts in air conditioner installation and can help you choose the perfect size for your space. Contact us today for all your air conditioning needs. 

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