Not sure what size you need? Text us the room, its length and width, and which way it faces. Our automated quote assistant replies straight away, at any hour.
As a rough guide, a room up to 20 m² needs about 2 to 2.5 kW, a room of 20 to 40 m² needs 2.5 to 5 kW, and an open plan area over 60 m² needs 5 to 9 kW. That’s the CHOICE room size chart. What size air conditioner you need also depends on insulation, sun, ceiling height and climate, so we confirm the size on site before we install.
The quick answer
- Room size gives you a starting range: about 2 to 2.5 kW for a bedroom or study up to 20 m².
- Ceiling insulation makes a big difference. In a CHOICE example, a 30 m² room needed 2.3 kW with roof insulation and 2.9 kW without it.
- Too big and the system short cycles and doesn’t dry the air well. Too small and it runs flat out more often.
- Our split systems run from 2.5 kW, supplied and installed from $1,814.51 including GST, up to 8 to 9.5 kW from $3,761.25.
What size air conditioner do I need for my room?
Start with the floor area. Multiply the length of the room by its width to get square metres, then find the row in the chart.
| Room size | Example rooms | Approximate capacity |
|---|---|---|
| Small, up to 20 m² | Bedroom, study, small kitchen | 2 to 2.5 kW |
| Medium, 20 to 40 m² | Bedroom with ensuite, small lounge | 2.5 to 5 kW |
| Large, 40 to 60 m² | Large bedroom, mid sized lounge, large kitchen | 4 to 6 kW |
| Extra large, over 60 m² | Open plan areas, large lounges | 5 to 9 kW |
The chart is from the CHOICE guide What size air conditioner do I need?. CHOICE calls it a rough guide, and the ranges are wide for a reason. Two rooms with the same floor area can need quite different sizes.
Why floor area isn’t the whole answer
CHOICE lists the details that change the size you need. The more of them you know, the closer the estimate.
| Factor | Why it matters |
|---|---|
| Ceiling height | A high ceiling means more air to cool, so the room needs more capacity. |
| Insulation | Ceiling insulation has the biggest effect. Without it, the room needs a larger unit. |
| Orientation | A large north or west facing window lets in a lot of summer heat. A shaded south facing window doesn’t. |
| Climate | A room in a hotter, more humid city needs more cooling than the same room somewhere cooler. |
Insulation is the big one. In the CHOICE example, a 30 m² room in Sydney needed 2.3 kW with roof insulation and 2.9 kW with none. CHOICE also worked out a 30 m² room in Brisbane at 2.6 kW, based on a corner room with 2.4 metre ceilings and an insulated roof.
Our view: if your ceiling has no insulation, it’s worth looking at before you buy. CHOICE says it can let you get away with a smaller air conditioner.
Too big or too small: what goes wrong
CHOICE’s advice is to choose a model that’s just the right size, or slightly larger than the room needs. Getting it wrong costs you either way.
| Size | What can happen |
|---|---|
| Too big | Frequent short cycles, a room that swings too hot or too cold, air that isn’t dehumidified enough, higher power use and more wear. |
| Too small | The unit runs at full output more often, dries the air out too much, uses more power and wears faster. |
CHOICE also warns that some online calculators and installers recommend more capacity than a room needs. That’s why a size has to be checked against the actual room, and floor area is just the start.
Our split system sizes and installed prices
We supply and install Haier, Mitsubishi Heavy Industries and Daikin split systems in five sizes, under ARCtick licence L181564 and QLD Electrical Contractor Licence 90552. Each price is for one system installed back to back on a single storey home, and it includes GST.
| Split system | Fits the CHOICE range for | Price including GST |
|---|---|---|
| 2.5 kW | Small and medium rooms | from $1,814.51 |
| 3.5 kW | Medium rooms | from $2,014.50 |
| 5.0 kW | Medium, large and extra large rooms | from $2,414.50 |
| 7.1 kW | Extra large rooms and open plan areas | from $2,814.50 |
| 8 to 9.5 kW | Extra large rooms and open plan areas | from $3,761.25 |
A wall bracket is an extra, at $104.50 including GST. Every size and brand is on our air conditioning prices page.
Text for a quote Call 07 4428 2766
How we confirm the size before we install
We can suggest a size from the measurements you text us. The installer then confirms it on site, in the room itself, before any work starts.
- MeasureThe length, width and ceiling height of the room, and any open areas that join it.
- LookWhich way the windows face, how much sun they get, and whether the ceiling is insulated.
- ConfirmThe size, the brand and a fixed written price including GST, before any work starts.
If you’d like to check a size yourself, the Australian Government’s heating and cooling advice points to the FairAir calculators from the Australian Institute of Refrigeration, Air Conditioning and Heating. You enter the room’s details and get a cooling load. Read how we install split systems across Brisbane, or see our air conditioning installation in Logan.
Common questions about air conditioner size
Can one big system cool the whole house?
A wall split system cools the room it’s in, and it can’t reach rooms behind closed doors. For several rooms, you can have a split system in each one, or a multi head system with one outdoor unit and several indoor units. Multi head systems are quoted after a site visit.
Does a bigger air conditioner use more power?
Usually, yes. The Energy Rating label guide says that of two correctly sized systems with the same star rating, the larger one uses more electricity. Our guide to air conditioner running cost shows how to work out the kWh.
What does the kW number on a split system mean?
It’s the cooling capacity: how much heat the system can move out of the room. It isn’t the electricity the system uses. The Energy Rating label shows that separately, as estimated energy use in kWh a year.
Which brand should I choose?
Choose the size first, then compare brands at that size. We supply Daikin split systems, Haier and Mitsubishi Heavy Industries.
Our advice
Use the chart to find a range, then text us the room’s measurements, which way it faces and whether the ceiling is insulated. We’ll suggest a size and confirm it on site, so you’re not paying for a system that’s too big or living with one that’s too small.
Get the right size and a fixed price
Text us the room, its measurements and which way it faces. Our automated quote assistant replies straight away, at any hour.
Text for a quote Call 07 4428 2766
Calls are answered Monday to Friday, 7am to 3:30pm. Or send the details online.
Prices current as of 5 October 2026 and include GST. Sources: CHOICE, “What size air conditioner do I need?”; Australian Government, energy.gov.au, “Heating and cooling”; Energy Rating, “Understand the Zoned Energy Rating Label”. This article is general information. It is not advice about your home.
Related guides
How to Prevent Air Conditioner Short Cycling
Air Conditioner Replacement Cost Brisbane: 7 Key Factors
Air Conditioner Electricity Usage: Calculate Costs- Air Conditioner Running Cost: Calculate It
- Do You Need a Licensed Electrician to Install an Air Conditioner in QLD?
All guides: electrical and air conditioning guides.
Licensed electricians and ARCtick refrigeration technicians, Queensland Electrical Contractor Licence 90552 and ARCtick L181564. We install and service split systems and do the electrical across Logan, Brisbane southside, Ipswich and the northern Gold Coast.
About Faze | Call 07 4428 2766 | Text 0489 275 747