What Does It Cost to Run Air Conditioning in Summer?
A reverse-cycle air conditioner delivering 5 kW of cooling, at a coefficient of performance of 3.5, draws about 1,430 watts. Run for 8 hours a day over a 90 day summer, with the compressor on 70% of the time, it uses 721 kWh, which costs about $239 at 33.14 cents per kWh.
Try your own numbers
Last checked 10/11/2026. Sources: South Australian Government: Calculate appliance running costs; Virginia Cooperative Extension: Estimating Appliance and Home Electronic Energy Use (typical wattages, 2020); Australian Energy Regulator: The Default Market Offer (tariff caps 2026-27); Essential Services Commission (Victoria): Victorian Default Offer price review 2026-27.
How these figures are checked. Sourced figures link to the publisher’s own page and carry a last-checked date; our own rules of thumb are labelled as such. Run by JB, an independent publisher based in Australia. Spotted a mistake? Email hello@calcfig.com.
How the cost of air conditioning is worked out
An air conditioner is rated by the cooling it delivers (kilowatts) and how efficiently it turns electricity into cooling. The electricity it draws is the cooling divided by the efficiency. A 5 kW system with a coefficient of performance (COP) of 3.5 draws 5,000 ÷ 3.5 = about 1,430 W. The COP of 3.5 is an assumption for the example, not a measured figure for any model: your unit’s specification sheet gives its rated power input, and the draw changes with the weather and how hard it is working.
1,430 W for 8 hours is 11.44 kWh at full power. A compressor does not run flat out all day, so the example assumes it is on 70% of the time: 8.008 kWh a day. Over 90 days that is 721 kWh, and at 33.14 cents per kWh the summer costs $238.85, or about $2.65 a day. The 33.14 cents is the example rate for the Ausgrid area; pick your own network area and the cost updates. The daily supply charge is not included because you pay it whether or not you run the air conditioner.
Time-of-use tariffs change the answer: if your plan charges more in the late afternoon and evening, when cooling is most used, the real cost can be higher than a single flat rate suggests.
Common questions
How many watts does a split system air conditioner use?
It depends on its size and efficiency. A 5 kW cooling system at a COP of 3.5 draws about 1,430 W while the compressor runs. Check the specification sheet for your model.
Does the compressor run all the time?
No. It cycles on and off to hold the temperature, and an inverter unit varies its speed. The calculator lets you set the share of time at full power; 70% is an example, not a rule.
Do time-of-use rates change the cost?
Yes. This page uses one flat rate. If your plan charges peak rates in the afternoon and evening, enter the rate that applies to the hours you run the unit.