An air conditioner’s size is crucial to give good results. But what if you are unsure and ask yourself, “What size air conditioner do I need?” Well, we have got your back.
This article will focus on your question, “What size air conditioner do I need” and a detailed guide about the right size. So, let’s dive in! 

Factors to Consider When Sizing an Air Conditioner

Before answering your question, “What size air conditioner do I need” Here are some details on the factors to consider when sizing an air conditioner:

Room size and square meterage

When choosing an air conditioner, it’s important to take the size of the room to be cooled into account. The larger the room, the larger the air conditioner capacity required to cool it effectively. The area of the room must be measured in order to determine the capacity needed to maintain the desired temperature.

Climate and weather conditions

The region’s climate and weather, where the air conditioner will be used, are additional crucial considerations. Greater air conditioning capacity is needed in areas with high temperatures and humidity.

Type and quality of insulation

The amount of insulation in the room affects how much cooling power is needed. The air conditioner will have to work harder than necessary because of significant energy loss caused by inadequate insulation. Insulation done right can keep a space cool and ease the strain on the air conditioner.

Number of occupants and their activities

The amount of people using the space and their activities can also have an impact on the necessary cooling capacity. More heat is produced in a room when there are many people present and there is a lot of activity, which can increase the cooling load on the air conditioner. 

Type and size of windows and doors

The type and size of the windows and doors in the room can also have an impact on how much cooling is needed. Large windows and doors add to the heat load of the area, which increases the air conditioner’s workload.

Location and orientation of the room

In determining the necessary cooling capacity, the location and orientation of the room are also important factors. Rooms that receive direct sunlight require more cooling than those that do not. In a similar manner, the location of the room within the building can influence the heat gain or loss.

Other factors 

Electronic devices, lighting, and the building’s chosen roofing material are a few additional variables that could have an impact on the climate control needs. When calculating the necessary cooling capacity, all of these factors should be taken into account.

Calculating the Correct Size for Your Air Conditioner 

Now, to the point, “What size air conditioner do I need.” Choosing the right size air conditioner is essential for maintaining a comfortable indoor temperature and keeping energy bills low. 

In Australia’s Sunshine Coast, where temperatures are frequently warm and muggy, selecting the proper air conditioner size is essential for maximizing performance and efficiency.

How much air conditioning is required depends on a number of factors, including the size of the room, the number of users, the amount of sunlight that will enter the room, and how well-insulated the building is.

If you don’t know “what size air conditioner I need” here is a way to calculate the correct size for your air conditioner; you can use the following steps:

A general rule is Room size (m2) x 150watts = AC size

  1. Make a room size calculation: To calculate the square meterage of a room, multiply the length and width of the space. As an illustration, a room measuring 5m by 4m would be 20 square metre.
  2. Multiply square metre by 150
  3. If there are people frequently walking in and out of the space, the capacity of the aircon will need to increase accordingly.
  4. Sunlight adjustment: Increase the capacity requirement by 10% if the space receives a lot of sunlight.
  5. If the room is inadequately insulated, the capacity requirement should be raised by 10%.
  6. Select an air conditioner with the appropriate kW rating: A product with a kW rating that is equal to or slightly higher than the required kW capacity is the best option.

For example: 20 m2  x  150 watts  =  3000 watts (3 kW)

So generally you would need a 2.5kw if there is minimal heat load and not used very often during the day. But if this space was in a work environment with a lot more electronics, doors opening frequently, used everyday during the middle of day, a 3.5kw unit would be recommended. 

Why is it essential to get the right size?

Knowing “what size air conditioner I need” is crucial. It is essential to get the right size of air conditioner for several reasons:


An air conditioner that is inadequately sized for the space it is intended to cool will have to work harder to maintain the desired temperature, which could lead to higher energy costs and more system wear and tear. 

On the other hand, an air conditioner that is too big for the room or space may experience short cycling, in which case it frequently turns on and off. This can lower the unit’s efficiency and shorten its lifespan.


A more efficient and effective way to maintain a comfortable temperature is with an air conditioner that is the appropriate size for the room or area it is trying to cool. Additionally, it will be able to reduce humidity, which will enhance indoor air quality and increase comfort in the area.


Long-term savings can be achieved by choosing the correct sized air conditioner. An air conditioner that is too big or small can lead to higher energy costs, more frequent repairs, and an earlier replacement date. Choosing the right size can also save you money by preventing the need for unnecessarily large or small air conditioners. 

Environmental impact

By minimizing energy use and lowering greenhouse gas emissions linked to the production of electricity, using an air conditioner that is the right size for the room or area can also reduce your environmental impact. This is crucial for reducing climate change and safeguarding the environment for upcoming generations.

Air Conditioning Sunshine Coast Capacity Requirements Per Room Size

If you are unaware of the right size AC you require, consider looking at an air conditioner room size calculator. Doing this will allow you to look at the right size and answer another question: “How many kw aircon do I need.” We have an air conditioner size guide to make choosing the right air conditioner easier. Let’s have a look at the air conditioner room size chart.

Room Size (square metre)

                  Kilowatts required


1.5 – 2kw


2.5 – 3.5kw


3.5 – 5kw






8 – 9kw




10 – 12.5kw


12.5 – 14kw


14 – 16kw

That’s A Wrap!

I hope this article now answers your question of “what size air conditioner do I need”. Selecting the right size air conditioner is crucial for achieving optimal comfort, energy efficiency, and cost savings.  

You can calculate the correct cooling capacity needed for your home or workplace by taking into account variables like the number of windows, insulation, electronic devices, people movement and other factors that may affect the heat load. 

To make sure you choose the right size air conditioner for your unique needs, you can also seek advice from a qualified HVAC technician or use sizing charts and calculators provided by air conditioner manufacturers. 

By making the right air conditioner investment, you can maintain the perfect temperature all year round at your home or workplace while reducing your energy consumption.