What size air conditioner do you need?

January 7th, 2013

Air Conditioners Appliance Questions

If you’ve already taken our advice about how to stay cool this summer and decided to purchase an air conditioner, then there are some important questions to ask in order to select the best unit for your needs.

Buying an air conditioner to suit the size of room you are trying to cool is very important. Air conditioners with a large cooling capacity will use more energy, while units that are too small will not cool the room properly, keeping you hot and bothered.

How big is the area you need to cool?

The most vital piece of information you need to have ready is the size of the space that you wish to cool.

You don’t have to be a mathematician to do so – simply multiply the length of the room by the width. Ceiling height may be considered a factor if you have particularly high ceilings, but to keep things simple just calculate the floor space.

Now we know that not every room is a perfect rectangle, or perhaps you may want to cool two rooms at once.

Aircon_infographic_151214 Large-Capacity Medium-Capacity Small-Capacity

Panasonic has a great online Air Conditioner Sizing Wizard to help you calculate your tricky space without any hassle. Just use the slider to select the length and width of your room and then choose the room shape from the options along the top of the page that best describes your space. Click and drag your cursor across the grid for a more accurate description of your room/s to correctly calculate how many square metres you need to cool.

Air conditioners are measured according to their output capacity, and Appliances Online stocks units ranging from 1.65 kW window air conditioners to 9.2 kW reverse cycle split systems.

As a basic starting point, you’ll need a MINIMUM 1-1.5 kilowatts of cooling capacity per 10 square metre of space that needs to be cooled.  If your home is well-insulated, this minimum capacity may be all you require, but uninsulated homes and homes located in Australia’s hotter regions will definitely need a more powerful air conditioner to enjoy efficient cooling.

According to Appliances Online product expert Colin Jones, size plays a significant role in achieving the cool result that you’re after.

“If you install an air conditioner which is too small for your room, it will never reach the desired room temp that you have selected.”


“At the same if you select a machine too big for the room, the cool air will bounce off the opposite wall and the machine will cycle off thinking it has reached the temperature selected.”

But before you jump online to make a purchase, there are some other important considerations:

What type of air conditioner are you after?

Air conditioners come in a variety of styles, some more suited to certain needs than others:

Some important factors to consider include:

  • Whether you rent or own your home
  • Your budget (for both purchasing and installation, as well as running costs)
  • Do you also need to heat the space in winter?

Appliances Online stocks popular portable air conditioner brands including Atlantic, Omega, Dimplex and De’Longhi, which is a great for anyone who is renting or is looking for a more flexible option. Portable A/C units can cool a room up to approximately 20 sq m and are considerably cheaper than their more permanent counterparts.

Window units are mounted through a window or wall, and best suited to smaller rooms. Some also have the option of being reverse cycle, which means that they also provide heat in the winter.

Split system air conditioners get their name due to the fact that the cooling unit is installed outside while the fan is mounted inside, and are ideal for larger areas. All split system models are also reverse cycle (provide a cooling and heating function), and many come with packed with features such as remote control, timers, washable air filters and user programs.

Appliances Online stocks leading split system and portable air conditioner brands:

Panasonic_180x80 Samsung_180x80 mitsubishi_180x80 Kelvinator_180x80 fujitsu_180x80 Delonghi_180x80 dimplex_180x80

What level of insulation does the room have?

Insulation is one of the most effective ways to improve energy efficiency around the home – keeping the summer heat out and the cool air inside your home for longer. In some cases, you may be able to cool an insulated room using a smaller, less powerful air conditioner than an uninsulated room, and also save a few dollars along the way.


Some Australian homes have either ceiling or wall insulation, while some households are lucky enough to have both.

The average uninsulated home gains 25 to 35 per cent more heat in summer through the ceiling alone compared to insulated homes, as well as 15 to 25 per cent more heat through the walls.

When combined with the size of your room, insulation plays an important part in determining what size air conditioner you require.  Insulated rooms can usually be cooled using an air conditioner with only the minimum recommended kW capacity, though this may vary depending on the location of your home, which way your windows are facing, and a number of other factors.

Contact our expert team on 1300 000 500 for more information on calculating the best air conditioner size for your insulated room.

Where are the windows and what direction do they face?

The other major source of heat in a room comes from the window.

Rooms with windows that face west may require a larger capacity air conditioner, especially if the windows are particularly large or there are a number of open doors to account for.

Of course, blinds and curtains can also act as a form of insulation, as well as external sources of shade such as trees, eaves and awnings.

What climate are you living in and where are your rooms situated?


The elevation and location of your house is also an important factor to consider. Australian is renowned for having a variety of climates, and while everyone may be looking to stay cool, there are a number of factors to consider.

Refrigerated air conditioners – including the portable variety – can cool and dehumidify rooms, so are suitable for both dry and humid climates.

Those in a drier climate may consider DeLonghi’s new range of Water-to-Air units as an alternative to the more traditional refrigerator variety. The innovative technology helps to remove heat from the room by efficiently pumping water upward over the condenser, producing a cooling effect.

As one last piece of advice, Colin suggests that the best type of air conditioner is one that suits you and your lifestyle – but maintenance is important.

“The average life of an air conditioner is 10 to 12 years, but that will depend on how often the unit is used. It is best to turn the machine on a few times a year to keep the gas moving in the unit.”

Remember, if you have any question about air conditioners, talk to an expert at Appliances Online.

Here’s Colin’s overview of the different types of air conditioner we offer at Appliances Online:

Elise is a Sydney writer who is passionate about the three F's - food, fitness and functionality. When she's not cooking up a storm in the kitchen, she's catching up on some TV while waiting for her sweaty gym gear to be washed and dried in record time. Her favourite appliance is a sandwich press, but she hopes to add a state-of-the-art coffee machine to her kitchen collection soon. Google+

4 responses to “What size air conditioner do you need?”

  1. martin warner says:

    Do you supply multi-head split system air conditioning systems?

    Please provide links.

    Martin Warner

  2. Mark Bristow says:

    Hi Martin,

    Unfortunately we do not currently carry multi-head split system air conditioners. Your best bet may be to get in touch with an air conditioning specialist.

    Our current range of split systems can be found here: http://www.appliancesonline.com.au/split-system-air-conditioner/



  3. Glow HCE says:

    Really it’s a nice post and helpful for people to select air conditioner. Thanks for sharing this post.

  4. Hassan says:

    I am looking to buy a portable AC for my college room (around 12 sqm). What do you recommend?

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