What your air conditioner really costs.
The number on the box is cooling output, not electricity. Here is what each type actually draws, per hour and per summer.
A 5kW air conditioner does not use 5kW
This is the single most useful thing to understand about air conditioning, and most running-cost articles get it wrong. The kilowatt figure on the box is cooling capacity — how much heat the unit can shift. The electricity it consumes doing that is a different, much smaller number, because an air conditioner moves heat rather than creating cold.
A unit sold as 5kW draws about 1.32kW. If you have read somewhere that your air conditioner costs $1.60 an hour, you have read a figure that multiplied the wrong number by your tariff. The real cost is closer to 42 cents.
| Sold as | Suits | Actually draws | Per hour | Per season |
|---|---|---|---|---|
| 2.5 kW | A bedroom | 0.50 kW | $0.16 | $112 |
| 3.5 kW | A larger bedroom or study | 0.87 kW | $0.28 | $195 |
| 5 kW | A living room | 1.32 kW | $0.42 | $297 |
| 7.8 kW | An open-plan living area | 2.36 kW | $0.76 | $530 |
| 14 kW | A whole house | 4.00 kW | $1.28 | $829 |
Input power for the split systems is from Mitsubishi Electric’s published MSZ-AP specifications. Costed at 32c/kWh. “Per season” assumes six hours a day across 180 days — set your own in the calculator below.
Three things that change the bill, and one that doesn’t
The temperature you set
Each degree below 24–26°C in summer can add around 10% to the energy used, because the compressor runs longer to hold a wider gap against the outside air. Setting 18 instead of 24 does not cool the room faster — the unit is already at full output either way — it only changes how long it keeps running once it arrives.
How many rooms you are conditioning
A ducted system draws about 4kW flat out, roughly three times a large split. That is only expensive if it is cooling bedrooms nobody is in. Zoning is what decides whether ducted is the cheap option or the dear one, and it is worth knowing which zones your controller actually isolates.
The hours, not the hourly rate
An hourly figure on its own tells you very little. The same living-room split costs about 1.65 on a six-hour day and 297 dollars across a season. What makes air conditioning the biggest line on a summer bill is not the unit — it is the number of hours it is left on.
And the one that doesn’t: switching it off and on
An inverter unit is at its most efficient holding a steady temperature. Turning it off whenever you leave the room and back on when you return makes it work hardest most often. For short absences, leaving it running at a sensible setting usually costs less than restarting it.
In winter, it is the cheapest heater you own
A plug-in panel heater converts electricity into heat at best one-for-one: put in 2kW, get 2kW of warmth. A reverse cycle air conditioner is not bound by that, because it is moving heat in from outside rather than generating it. The same unit that cools your living room in summer delivers around 6kW of heating for 1.62kW of electricity — 3panel heaters’ worth of warmth for less than the electricity one of them uses, which works out about 3.7 times cheaper to run.
It takes 3 of them to put out 6kW of heat, drawing 6kW between them. There is no version of resistance heating that does better than one-for-one.
The same 6kW of heat for 1.62kW of electricity — and you already have the unit on the wall.
Both deliver 6kW of heat for 6 hours a day across 120 days, at 32c/kWh — a typical New South Wales residential rate. Comparing the two units’ own input power instead would be the same capacity-versus-input mistake this page is about: a 2kW heater and a 5kW split do not warm the same room.
Running it on solar: honestly, it depends on the hour
Air conditioning and solar line up better than almost any other load. The hot part of the day is the sunny part of the day, so a system that is producing well is usually producing while you most want to be cool. A 6.6kW array on a clear afternoon makes more than enough for a ducted system at full output, and several times what any single split needs.
The honest limit is the evening. The 7pm peak, when most households turn everything on, has no sun in it. Across a season that split costs about $297 from the grid against roughly $46 if every hour of it ran on your own roof — and the truth for most homes sits between the two. Pre-cooling the house while the sun is still up is the free version of a battery, and it works better in a well-insulated house than a draughty one.
Work out your own
Sold as 5kW cooling (2,230W max input). Draws 1.32kW rated electricity.
Briefly draws several times that on start-up, for a second or two.
This one only runs for part of the year, which is why an hourly figure on its own tells you very little.
Most published running costs quote one national rate of about 33 c/kWh. Yours is on your bill, and it is the number that decides everything here.
Only applies to the hours it runs while the sun is up. After dark you are buying from the grid again — or from a battery.
Estimate only. Running on solar is costed at your feed-in rate — the earnings you give up by using the power instead of exporting it, not zero. Appliance figures verified 2026-10-03; default rates 2026-06-22.
Frequently asked questions
How much does it cost to run an air conditioner per hour in Australia?
A bedroom split rated at 2.5kW of cooling costs about 16 cents an hour at 32 c/kWh. A 5kW living-room unit is around 42 cents, a 7.8kW open-plan unit about 76 cents, and a ducted system serving a whole house about $1.28 an hour when it is working hard. Those are the figures for the unit running flat out — an inverter system drops well below them once the room reaches temperature.
Why does my 5kW air conditioner not use 5kW of electricity?
Because the rating is cooling output, not electricity input. An air conditioner moves heat from inside to outside rather than creating cold, so it delivers three to five times more cooling than the power it consumes. A unit sold as 5kW draws about 1.32kW. This is the most common mistake in published running-cost tables, and it overstates air conditioning by three to four times.
Is ducted air conditioning more expensive to run than splits?
Per hour, yes — a ducted system draws roughly three times a large split. But that compares a whole house to one room. The real question is whether you are conditioning rooms nobody is in. A zoned ducted system running two zones can cost less than three separate splits doing the same job; an unzoned one cooling five bedrooms at midday is the most expensive way to be comfortable in one of them.
What temperature should I set it to?
Between 24 and 26 degrees in summer, and the reason is money rather than virtue. Each degree you set below that range can add around 10% to the energy the unit uses, because the compressor has to run longer to hold a bigger gap against the outside temperature. Dropping from 24 to 20 on a hot day does not cool the room faster — the unit is already working at full output — it just makes it run for longer once it gets there.
Is reverse cycle cheaper than a plug-in heater in winter?
Dramatically, and it surprises people. A 2kW panel heater turns 2kW of electricity into 2kW of heat — that is the best a resistance heater can ever do. A reverse cycle unit delivers about 6kW of heat for 1.62kW of electricity, because it is moving heat rather than making it. Matching that 6kW with plug-in heaters would take three of them drawing 6kW between them, so for the same warmth the air conditioner costs roughly a quarter as much to run. Compare it heater-for-heater and the gap looks small, because one 2kW heater simply is not warming as much room.
Can solar run my air conditioner?
During the day, comfortably. A 6.6kW system on a clear afternoon produces more than enough for a ducted unit at full tilt, and far more than any single split needs. The catch is timing: the hottest part of the afternoon still has good sun, but the 7pm peak most households cool through does not. Without a battery you are buying that evening power from the grid at 32 c/kWh. Pre-cooling the house while the sun is still up is the free version of a battery.
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