Enquire Now
October 12, 2021

What Size Air Con Do I Need? – Our Top Tips

Author: Lance Wiggers

Thinking of investing in an air conditioning system? It’s important to consider what type and size air con is right for you. After all, your air conditioner can have a big impact on your comfort, energy usage and power bills.

Choose an air con that’s too small and you risk sweltering in summer despite having the system on full blast. Choose an air con that’s too big and it could chew through electricity, driving up your power bill.

Air Con Mandurah

So, what size air con do I need?!

Figuring out what size air con you need can be quite involved. But don’t worry, we’ll walk you through all the factors you need to consider. If you’ve still got questions, chat with our air con specialists at iBreeze. We’d be happy to help.

What type of air conditioner is right for me?

Before you decide what size air conditioner you need, it’s important to choose the right system type for your household. The two main air conditioning systems are ducted and split.


Ducted air conditioning provides cooling throughout the entire house via a set of ducts in the ceiling cavity. Refrigerative systems use a chemical refrigerant to cool the air and provide precise climate control inside the home.

Evaporative ducted air conditioning relies on the natural phenomenon of evaporation to provide cool air throughout the home. These systems are much cheaper to run than refrigerative systems but don’t provide the same level of climate control.


Split air con systems provide cool air to one room via a wall-mounted unit. They are refrigerative systems, using a chemical refrigerant to provide refreshing cool air to the room. The warm air is released outside of the home via an outdoor unit.

Multi-head split systems are essentially the same as normal split systems except you can have multiple indoor units connected to one outdoor unit. This way you can cool two or more rooms without installing multiple outdoor units.

Room size vs air conditioner size

The size of your room/s is one of the most important factors to consider when deciding on your air conditioner size. Rooms with a larger volume will take more energy to cool and may require a more powerful system.

If you are wanting to install a split system in one room, take note of the total room volume by measuring the length, width and ceiling height of the room.

If you are wanting to install ducted air conditioning, calculate the total volume by adding the volume of each room together.

You can get a rough estimation of how many kW you need for your system by following the calculations below.

  • 1) For 2.4m ceiling height, calculate: Area of room/s (m2) X 150 (watts) / 1000
  • 2) For 2.7m ceiling height, calculate: Area of room/s (m2) X 160 (watts) / 1000
  • 3) For 3m ceiling height, calculate: Area of room/s (m2) X 175 (watts) / 1000

These calculations are a good place to start, but they won’t give you an accurate air con size. To ensure you get the ideal size, chat with an air con specialist who can give you tailored advice.

Other factors you should consider before choosing your size

Although room size is important, it’s not the only factor that you should consider before choosing your air conditioner size. Three other key factors are orientation, location and insulation.


What way is your room facing? Do you have large north or west-facing windows? Is the northern side of your house shaded during summer? Your answer to these questions can affect how much power your system needs.

Large north or west-facing windows can let in a lot of heat, requiring more energy to keep the room cool. On the other hand, rooms with shaded south-facing windows will tend to stay cooler throughout the day and will require less energy to cool down.


Air con requirements can vary greatly depending on where you live. Air conditioning in Mandurah, Perth and other warm regions will require a more powerful air conditioner than cooler places like Hobart and Melbourne.


Are your walls and ceiling insulated? Insulation slows down the rate of heat gain in summer and heat loss in winter, helping keep your home a more comfortable temperature. Heating and cooling is more energy efficient in homes that are well insulated. The level of insulation in your home could affect the size air con you need.

Need help choosing the right air con size?

The team at iBreeze are here to help. We provide air conditioning to Rockingham, Mandurah and surrounds and can help you choose the ideal system for your home. Chat with us today and get the expert advice you can trust with none of the pushy sales talk.

Lance Wiggers
Lance Wiggers is the founder and managing director of iBreeze, having started the company back in 2016. His expertise spreads across air conditioning services, solar power and wood heating to provide customers with a more comfortable living or working space. Lance's tailored approach means he always chooses the solution best for your specific situation. You might have the pleasure of dealing with Lance as your first point of contact when you enquire with the iBreeze team!
Your Comfort, Our Priority Get in Touch

For energy efficient, effective heating and cooling solutions all year round, reach out to our team of specialists. We’ll deliver the highest comfort to both your residential and commercial space, no matter the size or scale.

Sunday Closed

Monday 9:00am – 5:00pm

Tuesday 9:00am – 5:00pm

Wednesday 9:00am – 5:00pm

Thursday 9:00am – 5:00pm

Friday 9:00am – 5:00pm

Saturday Closed