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Based on 36 reviews

What Size Air Conditioner Do I Need?

When it comes to air conditioners, size does matter. However, bigger is not always better.

On one side, if your aircon is too small it will never be able to achieve your desired temperature. However, you cannot just of out and buy the largest aircon and say job done.

If your AC system is too large the purchase price and ongoing power bill will be unnecessarily high. So, unless you have money to burn you are better off buying an air conditioner that is just the right size.

Brand quality is another factor in choosing the perfect air conditioning system, but in this article, we will just stick to talking about the size.

Read on to learn the factors you should consider when choosing an AC system, how to find the air conditioning size for your needs and what happens if you get it wrong.

Woman staring and thinking with question marks around her

Recommended Air Conditioning Size for Your Room

In a rush? Here's a quick estimate of the air conditioning capacity based on the size of the room that needs cooling.

Room SizeAir Con CapacityExample
Small rooms (20m² or less)2 kW - 2.5 kW2.6 kW
Medium-sized rooms (20-40m²)2.5 kW - 5 kW3.5 kW
Large rooms (40-50m²)4 - 6 kW5.0 kW
Very large rooms (60m² or more)5 - 9 kW7.1 kW

However, please be aware there are several other factors that could affect the recommended capacity of your air conditioning unit. These are discussed below.

Electrician with orange hard hard inspecing a fuse box.

Calculating The Right Size

Many air conditioner models come in various sizes. If you want to calculate the exact size you should get manually, here's how you do it.

  • Find the area of the room (length x width).
  • Multiply the area of the room by 150 kW (estimated kW/m2 for standard rooms).

This will give you the estimated cooling capacity (in kW) that you need for your room.

Bear in mind this is just an estimation. Read about the other factors below that affect the AC's cooling capacity.

Electrician with orange hard hard inspecing a fuse box.

Factors That Affect the Air Conditioner Size You Need

On top of the size of the room, which is the main determining factor, you also need to consider the following:

  • The number of people in the room - more people mean more heat!
  • The height of the ceiling - the higher the ceiling, the more air volume there is to be cooled.
  • The orientation of the room - rooms that face the sun will heat up faster than rooms that don't.
  • The number and types of windows - windows let in heat from the sun which can make your room warmer.
  • Insulation - a well-insulated room will remain cooler for longer compared to a poorly insulated room.

These are just some of the factors you should consider when calculating the cooling capacity that you need for your room.

That said, use a smaller multiplier (140) for rooms that are well insulated, have a shorter ceiling, and are protected from the sun.

For higher ceiling rooms which are more likely to hold many people at once, you can use a higher multiplier (160) instead.

Of course, the easiest way to know the air conditioning size that you need is by consulting with a professional. They can help you choose the right air conditioner based on the factors that we mentioned earlier.

With their level of experience, they can do this just by looking at the room. Not to mention, they can also install your air conditioner properly to ensure that it works correctly and efficiently.

Large empty office showing ceiling with lights and aircon vents.

What Happens if You Choose the Wrong Size?

As mentioned, choosing the right air conditioning size is very important when buying an air conditioner.

Choosing an air con that is too large results in shorter cycles which does not leave enough time to dehumidify and remove moisture. This can result in a cold and clammy room.

In addition, the frequent on/off cycles can also cause premature wear and tear to your air conditioning unit.

On the other hand, an air conditioner that is too small will have to work overtime just to maintain the desired temperature in your room.

Not only does this make your unit less energy efficient, but it may also never dehumidify your room.

Woman in cold room with aircon remote in her hand.

Final Thoughts

Choosing the right air conditioner size is important if you want to have an efficient and effective cooling system in your home.

Remember to consider the factors that we mentioned when calculating the cooling capacity that you need for your room.

If you're still unsure, then it's always best to consult with an industry professional like us.

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