What Size Air Conditioner Do I Need?

By the time July rolls around, we’re typically so over winter. And then spring raises its sweet head, and the temps start to rise.

But then spring quickly p*sses off, and all of a sudden, it’s a wave of unwelcome, uncomfortable, unrelenting heat.

Yep. Aussie summers can be brutal.

Third-degree burns from the car seat buckle. Toasted feet if you cross the road without your thongs. And, the bl**dy magpies.

There’s not much you can do about the heat once you leave the house or the car. 

But there is something you can do to create the perfect, climate-controlled oasis inside your home.

But we know the search for that perfect air conditioner can do your head in. 

What size?
What type?
Which brand?

Hey — Don’t stress! This is where Hello Breeze saves the day. We’re here to make your life just that little bit easier.

No, we can’t help you deal with sullen teenagers. Or take the mother-in-law of your hands.

But we can help you choose the very best air conditioning system in Australia for your home, lifestyle and budget.

Whether you live in banana-bender country or the Apple Isle. Our air conditioner size guide will help you work out how to create the perfect climate in your home.

But first, are you after a reverse cycle split system or a gas ducted system

Let’s take a quick squiz at the diff to make sure you’re looking at the best system for your needs.

Split System Air Conditioners

Split system air conditioners are the most common type of AC found in Australian homes. If you live in a small house or need a unit for one room, it’s a great, energy-efficient option.

Split system air conditioners consist of two units. An indoor evaporative heat exchanger mounted on your indoor wall and an outdoor condensing heat exchanger.

Split systems are a tad cheaper and easier to install than ducted air conditioning systems. However, they aren’t suited to large rooms, double-storey properties, or homes with a flat roof.

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Ducted Reverse Cycle Air Conditioners

Ducted reverse cycle air conditioners are super-efficient systems that add value to your home. 

Air conditioning with ducting works by transferring hot or cold air to your entire home through ducts installed in your roof or floor.  

Zoning control allows you to adjust the temperatures of each room individually. Simply open the MyAir Zoning app and switch on the aircon in any room of your home, no matter where you are.

Ducted reverse cycle air cons cool down rooms quickly in any kind of climate - particularly humid areas.

Now, let’s talk about sizing.

What Size Air Conditioner Do I Need?

What size air conditioner do I need?

Of course, when considering “what size split system do I need?”, room size is the first thing to ponder.

However, other factors play an essential role when choosing the correct size unit for your room.

The following five features will have the most significant impact on the size of the AC unit you'll need.

1. Room Size

Yes, size does matter. Choosing an AC that’s too big or too small will not only affect its performance, but you’ll quickly notice it on your power bill. Heads up — you won’t be happy.

The air conditioner size guide below will help you choose a suitable air conditioner capacity.

Room sizeExampleCapacity 
Up to 20m2Bedroom, study, small kitchen2 to 2.5kW
From 20 to 40m2Bedroom with an ensuite, small lounge2.5 to 5kW
From 40 to 60m2Large bedroom, mid-sized lounge4 to 6kW
60m2 and aboveOpen-plan areas, large lounge5 to 9kW

So, what happens if you don’t hit the ‘Goldilocks’ size?

Why Size Matters? Air Conditioner Size Guide.

Choose a model with a kW capacity that's either just right or slightly higher than you need. 

For example, let’s say you want to cool bub’s room which is 20m². So, according to the air conditioner size guide above, you would choose a unit between 2.0 and 2.5 kW. We recommend you upsize slightly and go with the 2.5kW model.

2. Noise

Some systems can generate a boat-load of noise, and you won’t be particularly jazzed about that when you’re working or sleeping. A noisy outdoor unit can also p*ss off the neighbours.

Noise level is typically measured in decibels — dB(A). Standard air-con units operate anywhere between 18 and 60 dBA. 

The technical information for the brand you select will show the indoor sound levels for different stages of operation. For example:

Let’s put the noise levels into context. Watching the news at a normal volume — not Grandad volume — usually produces around 60 dB(A), and our regular indoor voices reach about 40 dB(A). 

So, if your indoor unit operates at 60 dB(A), it could very well interfere with your convos or your Netflix binge. 

The quietest units are around 18 to 24 decibels—comparable to the sound of a desk fan.

3. Home Insulation

Ceiling insulation is a total game-changer for energy efficiency. Insulation can vastly impact the size of the air conditioner you’ll need.

Home Insulation

If you don't have roof insulation, consider installing it. 

Not only will it save you money on your power bill in the long run, but you can get away with buying a smaller, cheaper air conditioning unit.

4. Location

AC capacity depending on where you live
AC capacity required for a 30m² room depending on where you live

Where you live can significantly affect the size of air-con you need. 

For example, as you can see, Brisbanites would need a more powerful air conditioner for cooling than the same sized room in Tassie. 

You also have to consider the orientation of your room’s windows. West or north-facing windows can let in a sh*t load of summer heat. South-facing windows will require less energy to cool the room.

And, how about the ceiling height of the room? Yes, floor space is important, but so is total volume. So, a room with high ceilings will require more energy to cool.

5. Energy Efficiency

All new A/Cs come with a Zoned Energy Rating Label (ZERL). The ZERL provides a seasonal efficiency rating for three Aussie climate zones. 

Which are:

  • hot, 
  • average, and 
  • cold.
Air conditioner size guide
Source: Energy Rating Aust.

Ratings run up to 10 stars for both heating and cooling. Clearly, the more stars, the more energy-efficient your AC unit is. 

How Do I Calculate What Size Air Conditioner I Need?

Because we thought of everything, you can find an air conditioner size guide calculator on our home page.

You just need to pop your room size:

And ceiling height:

Air con size calculator

And our calculator will accurately predict the best-sized unit for your room:

Air conditioner size calculator

But don’t forget to consider the other factors we discussed above.

Don’t forget, the Hello Breeze team of rockstars is on hand to help walk you through the process of calculating the right-sized unit and your options. 

Want more info on wall-mounted split systems or ducted air conditioners? Check out our installation guide and our super-easy booking process.

We can also help you find the most energy-efficient systems on the market, the best ACs for a small room, or the overall best air conditioners in Australia.

Whatever heating and/or cooling solutions you’re looking for to create a chilled or toasty oasis in your home, we’ve got you covered.

Give us a bell about our high-quality air conditioners by brands you can trust. Call on 1300 712 732, or ask us for a quote!


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