Owner Guide
Best Air Conditioner Temperature Settings
Finding the best air conditioner temperature settings is less about one magic number and more about matching the set point to the season, the time of day and the people in the room. This guide gives sensible starting points for Australian homes, explains why they work and shows how to fine tune them without wasting power.
Start Here
What Is the Best Temperature to Set Your Air Conditioner?
For most households, a cooling set point between about 25 and 27 degrees feels comfortable on a hot day. In winter, a heating set point of roughly 18 to 20 degrees keeps living areas cosy. These ranges reflect long standing Australian government energy advice and suit many homes well.
Why not go lower in summer or higher in winter? Because the further the set point sits from the outdoor temperature, the harder the system works. Moderate settings let the compressor ease back once the room is comfortable, rather than straining around the clock.
Of course, everyone feels temperature differently. Age, health, clothing and activity level all matter. Use these ranges as a starting point, then adjust one degree at a time until the room feels right.
Summer Cooling
Start around 25 to 27 degrees. Raise it a little if the room feels cool and the air is dry.
Winter Heating
Start around 18 to 20 degrees. Living areas can sit at the warmer end, bedrooms at the cooler end.
Overnight
Sleep usually comes easier in a slightly cooler room, so ease the set point back at bedtime.
The Science
Why Does the Set Point Matter So Much for Running Costs?
An air conditioner does not produce cold or heat from nothing. Instead, it moves heat between indoors and outdoors. The bigger the gap between the two, the more work it must do to keep that heat moving the right way.
Picture a summer afternoon when it is 36 degrees outside. Holding the room at 25 degrees asks the system to maintain an 11 degree gap. Asking for 18 degrees nearly doubles that gap. As a result, the compressor runs harder and longer, and the bill reflects it.
Inverter systems make this effect easier to see. They slow down smoothly once the room nears the set point. With a moderate setting, they often settle at a low, quiet speed. With an extreme setting, they may never reach that point at all. Our guide on inverter air conditioners explained covers how this works.
- Each step closer to the outdoor temperature reduces the load on the system.
- Moderate set points let inverter units run at efficient lower speeds.
- Extreme settings rarely make rooms comfortable any faster.
- Steady settings are usually gentler on equipment than constant changes.
Summer
What Temperature Should You Set in Summer?
Hot weather tempts people to grab the remote and press the down arrow until it stops. It feels logical, yet it rarely helps. Most units cool at roughly the same rate regardless of the set point, so a low setting only means the unit keeps running after you are comfortable.
Instead, aim for a set point around 25 to 27 degrees. On very humid days, you may feel comfortable at the warmer end if you use Dry mode or a lower fan speed to remove moisture. Dry air simply feels cooler on the skin.
Hot and Dry Afternoons
Typical of Adelaide and Perth in high summer. Cool mode at a moderate set point, with blinds closed against the western sun, works best.
Warm and Humid Days
Common in Brisbane and coastal Sydney. Moisture removal matters as much as temperature, so Dry mode or a slightly lower fan speed in Cool mode can feel better.
Changeable Weather
Melbourne summers can swing sharply in a single day. A timer that starts cooling before the heat peaks, then a cool change bringing open windows, often works well.
Ceiling fans pair nicely with cooling. Moving air makes you feel cooler, so you can often set the air conditioner a degree or two higher without losing comfort. For the different modes and when to use them, see air conditioner modes explained.
Winter
What Temperature Should You Set in Winter?
Reverse cycle heating is efficient, but it still costs more the higher you push the set point. A range of about 18 to 20 degrees suits most living spaces. Bedrooms and rooms used for active tasks can sit lower.
Warm air rises, so heat collects near the ceiling. Aiming the louvres downward pushes warm air towards the floor where you actually sit. On some units, a ceiling fan running on a slow reverse setting can also help push warm air back down.
Winter also brings defrost cycles in cold, damp weather. During defrost, warm air pauses for a short time. Raising the set point will not prevent this, because defrost is triggered by frost on the outdoor coil, not by the room temperature. For more on preparing for the cold months, see how to prepare your air conditioner for winter heating.
Dress for the Season
A jumper and warm socks let you feel comfortable at a lower set point. It sounds simple, yet it makes a real difference.
Stop the Draughts
Door snakes, sealed gaps and heavy curtains keep warm air inside, so the system works less to hold the temperature.
Bedtime
What Is the Best Air Conditioner Temperature for Sleeping?
The body naturally cools down as it prepares for sleep. A room that is slightly cooler than daytime living areas supports that process. Many people sleep well with cooling set around 25 or 26 degrees in summer and heating around 16 to 18 degrees in winter, combined with suitable bedding.
Sleep functions help here. On most brands, sleep mode slowly shifts the set point by a degree or two over the first hours of the night. In summer it rises slightly, and in winter it drops slightly. This mirrors the body’s own rhythm and saves energy.
Pre Cool or Pre Warm
Run the unit for a while before bed so the room is comfortable when you lie down.Switch to Sleep or Quiet
Lower fan noise and gentle set point changes reduce disturbance during the night.Set an Off Timer
If you prefer, let the unit switch off a few hours after you fall asleep, once the room has settled.Direct the Airflow Away
Angle louvres so air does not blow directly onto the bed, which can feel cold and dry out your throat.
Young children and older people can be more sensitive to heat and cold. For them, a consistent overnight temperature without big swings is usually more important than saving a little energy.
Away From Home
Should You Leave the Air Conditioner Running When You Go Out?
This question has no single answer, because it depends on how long you are away and how extreme the weather is. As a general rule, switch off for longer absences, such as a full working day in mild weather. Turning it off removes the running cost entirely.
For short trips, or on extreme days, the picture changes. A house that bakes all afternoon becomes very hot, and pulling it back down takes a long run at full output. In those cases, a timer that starts the unit before you return can deliver comfort on arrival without running all day.
Usually Switch Off
- A full day out in mild or warm weather
- Rooms nobody will use for several hours
- Overnight in spare bedrooms
- Holidays and trips away
Consider a Timer or Schedule
- Heatwave days in poorly insulated homes
- Homes with pets that need a safe temperature
- Cold winter evenings when you return after dark
- Bedrooms you want comfortable at bedtime
App control makes this much easier. Our guide to WiFi and app control explains how to set schedules and switch the system on from your phone on the way home.
Room by Room
Do Different Rooms Need Different Settings?
Yes. A west facing lounge with big windows has very different needs from a shaded bedroom on the south side. Treating every room the same often leaves some too cold and others too warm.
Consider how each room is used. A home office where someone sits still all day may need a slightly warmer winter setting than a kitchen where someone is moving around. Likewise, a nursery may need a steadier temperature than a guest room.
Living Areas
Moderate settings, with blinds and curtains doing some of the work during peak sun hours.
Bedrooms
Slightly cooler than living areas, using sleep and quiet functions overnight.
Home Offices
Steady settings to suit long periods of sitting, with airflow angled away from the desk.
Ducted systems with zoning make room by room control easier. Closing zones in unused rooms reduces the area being conditioned. Multi head split systems let you set each indoor unit separately, provided they all share the same mode.
Beyond the Remote
What Else Affects How Comfortable a Set Point Feels?
Two rooms at the same temperature can feel quite different. Humidity, air movement, sunlight and nearby surfaces all change how warm or cool you feel. Paying attention to these factors lets you choose a gentler set point without losing comfort.
- Humidity: damp air feels warmer in summer and colder in winter.
- Air movement: a gentle breeze from a fan feels cooler than still air.
- Radiant heat: sun on your skin, or a hot window nearby, makes you feel warmer.
- Cold surfaces: bare tiles and single glazed windows draw warmth away in winter.
- Clothing and activity: lighter clothing in summer and layers in winter change your comfort zone.
- Clean filters: a well maintained unit delivers the airflow it was designed for.
That last point is easy to overlook. A system with dirty filters cannot deliver its full output, so owners often lower the set point to compensate. Our guide on how to clean air conditioner filters fixes that quickly.
Avoid These
Which Temperature Setting Habits Waste the Most Energy?
Most wasted energy comes from a handful of everyday habits rather than from the equipment itself. The good news is that each one is easy to change. Once you spot them, small adjustments quickly become second nature.
Fighting the Thermostat
Several people in one house often nudge the remote up and down all day. The system never settles, and nobody ends up comfortable. Agreeing on a household setting, then adjusting clothing instead, works far better.
Cooling With Windows Open
It happens more than people admit. A window left ajar in another room lets conditioned air escape and hot air pour in, so the unit runs flat out without ever catching up.
Using Heat and Cool in the Same Day Without Need
On mild days, a cool morning and a warm afternoon do not always need the air conditioner at all. Opening the house to a breeze or closing it against the sun may be enough.
Forgetting Timers and Schedules
Old timers can quietly start the unit in empty rooms for months. Check the timer settings at the start of each season and clear anything you no longer need.
Fixing these habits costs nothing. Combined with moderate set points, they often deliver a bigger saving than any single upgrade. Our guide on how to reduce air conditioner running costs lists more ideas.
Good to Know
What If the Room Never Reaches the Set Temperature?
A unit that runs and runs without reaching the set point is telling you something. Sometimes the cause is simple, and sometimes it points to a fault.
Open more detail
First, rule out the easy causes. Check the filters, confirm the mode is correct and close doors to the rest of the house. Make sure furniture or curtains are not blocking the indoor unit, and that leaves are not packed around the outdoor unit.
Next, consider whether the unit is the right size for the room. An undersized system may cope on mild days but fall behind during a heatwave or a cold snap. Our guide on what size air conditioner you need explains how capacity is chosen.
If those checks do not explain it, the system may have a fault. Low refrigerant, a failing fan motor or a faulty sensor can all limit performance. Our troubleshooting pages for Samsung not cooling, Panasonic not cooling, Fujitsu not heating and Mitsubishi not heating cover the common causes by brand. Refrigerant work must be done by an ARCtick licensed technician.
Questions
Frequently Asked Questions
Does Setting a Lower Temperature Cool the Room Faster?
Generally, no. Most units cool at a similar rate regardless of the set point. A lower setting just makes the unit keep running longer after you reach comfort.
Is 25 Degrees a Good Setting for Summer?
For many households, yes. It sits within the commonly recommended cooling range of about 25 to 27 degrees and balances comfort with running costs. Adjust up or down a degree to suit your home.
What Is a Sensible Heating Setting for a Living Room?
Somewhere between 18 and 20 degrees suits most living areas. Warmer clothing and good draught sealing help you stay comfortable at the lower end.
Why Does My Room Feel Colder Than the Number on the Remote?
The unit measures temperature near its own sensor, often at the indoor unit or controller. Cold walls, floors and draughts can make you feel cooler than that reading.
Should I Change the Temperature Often?
Constant changes rarely help. Pick a moderate setting, give the room time to settle, then adjust by one degree if needed.
Is Auto Mode Good for Holding a Steady Temperature?
Auto can work well in mild seasons. In strong summer or winter conditions, choosing Cool or Heat directly usually gives more predictable results.
Should Pets Change My Temperature Settings?
Pets left at home on hot days need a safe, shaded and ventilated space. A schedule or a moderate cooling setting can help on extreme days. Always provide water, and remember that some breeds handle heat poorly, so ask your vet for specific advice.
Can Temperature Settings Affect How Long My Unit Lasts?
Moderate settings reduce strain on the compressor and fan, which supports a longer working life. Regular servicing matters even more.
Get Help
Where Can You Book a Technician If Comfort Does Not Improve?
If sensible settings, clean filters and good habits still leave rooms uncomfortable, a licensed technician can check the system properly. We book technicians across our service cities.
Find your city: Sydney air conditioner repairs, Melbourne air conditioner repairs, Brisbane air conditioner repairs, Perth air conditioner repairs and Adelaide air conditioner repairs. Prefer to start with self checks? Visit the troubleshooting hub, or see our main air conditioning service Australia page for an overview.
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Reviewed by AC repair and service specialist on 22 October 2026. How we write our articles