Rebates & costs
What temperature should you set your air conditioner?
Set your air conditioner to 24 to 26°C in summer and 18 to 20°C in winter. That is the NSW Government’s advice. Every degree further from it can add around 10% to what the system costs to run.
5 min read
The short answer
Why 24 to 26 degrees works in summer
Comfort depends on the gap between inside and out and on humidity as much as on the number itself. Coming in from a 35 degree afternoon, 25 feels cool. Set it to 20 and the system runs much longer to hold a temperature that feels cold once you have settled.
The closer the setting is to the outside temperature, the less heat the system has to move and the less power it uses. That is where the NSW Government’s figure of around 10% per degree comes from.
Settings for common situations
| Situation | Setting |
|---|---|
| Hot summer day | Cool mode, 24 to 26°C, fan on auto |
| Humid but mild day | Dry mode or cool mode at 25 to 26°C |
| Summer night | Cool at 25 to 27°C with sleep mode |
| Winter day | Heat mode, 18 to 20°C |
| Winter night | Heat at 17 to 18°C or off with a timer to warm the room before you get up |
The day and winter ranges are the NSW Government’s advice. The night settings are a common starting point rather than official advice.
When the right setting still feels wrong
On muggy days the room can sit at 25 and still feel sticky. That is humidity, which is what dry mode is for. Our guide to air conditioner dry mode explains when to switch. If you are not sure which button is which, see air conditioner remote symbols explained.
If the system cannot hold 25 on a hot afternoon, the setting is not the problem. Either it needs a clean or it is too small for the room. Dirty filters are the ten-minute fix. Beyond that, compare the room against our guide to what size air conditioner you need or book an air conditioning service.
Work out what your setting costs
Our guide to what it costs to run an air conditioner shows how to work out a yearly figure from the power your system draws, the hours it runs and the rate on your own power bill. Apply the 10% a degree guide to that figure to see what moving from the setting you use now to 25 is worth over a summer.
Common questions
- Does setting the air conditioner to 18 cool the room faster?
- No. The system cools at the same rate whatever you set, until it reaches the target. A lower setting only means it keeps going past the point where you would have been comfortable. It uses more power doing it.
- What temperature should I set my air conditioner at night?
- A degree or two warmer than during the day in summer, around 25 to 27°C, suits most people once they are asleep. Sleep mode does this for you by easing the setting up over the first few hours.
- Is it cheaper to leave the air conditioner on all day?
- For a room nobody is in, usually not. Switching off when you leave and using the timer to start it half an hour before you get home uses less power in most houses. During a heatwave in a poorly insulated home the gap narrows, because the system then has to pull a very hot house back down.