One of the most common questions we hear is simply: 'what size air conditioner do I need?' It is an important question, because sizing is one of the biggest factors in whether you will be happy with your system. Both undersized and oversized units cause problems.
Why sizing matters
Air conditioner capacity is measured in kilowatts (kW). Get it wrong and you feel it every day:
- Too small — the system runs constantly, struggles on hot days and wears out early
- Too large — it short-cycles, wastes energy, and controls humidity poorly
- Correctly sized — it reaches temperature comfortably and runs efficiently
What affects the size you need
There is no single number that fits every room of a given size, because several factors come into play:
- Floor area and ceiling height of the space
- Size, number and orientation of windows
- Quality of insulation in walls and roof
- Which direction the room faces and how much sun it gets
- How many people typically use the space
- Whether the area is open-plan or closed off
Melbourne's orientation matters too — west-facing living areas that cop the afternoon sun often need more capacity than their floor area alone would suggest.
Why professional sizing beats a rule of thumb
Online calculators and rough rules can give you a ballpark, but they cannot see your home. A professional load calculation considers all of the factors above together, which is how you avoid the expensive mistake of installing the wrong system. It is closely tied to choosing the right air conditioner in the first place.
Getting it right the first time
Because sizing depends on so many variables, the most reliable approach is an assessment of your actual home. Request a quote and we will recommend the right capacity for your space — whether that is a single split system or a zoned ducted system.
