Aircon Running Cost Calculator

It estimates what an air conditioner costs to run per hour, per day and per month. Enter the unit’s capacity (BTU or tons) and efficiency — or the input power straight off its rating plate — plus how long it runs and what you pay per kWh, and it works out the electricity used and what that costs.

Electrical input = cooling capacity ÷ efficiency (EER/COP), so a 12,000 BTU (1 ton, 3.5 kW) unit at an EER of 3.5 draws about 1 kW. That is scaled by the average compressor load, multiplied by your hours of use to get kWh, and multiplied by your electricity price. So 1 kW at 75% load for 6 hours is 4.5 kWh a day — at $0.25/kWh, about $1.13 a day or $34 a month.

As a rule of thumb, a modern split unit draws about 1 kW of electricity per ton (12,000 BTU) of cooling: roughly 700–1,100 W for a 12,000 BTU (1 ton) unit and 1,500–2,200 W for a 24,000 BTU (2 ton) unit at full output. The real average is lower, because the compressor rarely runs flat out for the whole session.

Both are efficiency ratios: cooling (EER) or heating (COP) output divided by electrical input. An EER of 3.5 means 3.5 kW of cooling for every 1 kW of electricity. Find it on the unit’s energy label or datasheet — modern inverter units are typically 3 to 4, and the higher the number, the cheaper the unit is to run.

Roughly, yes — a reverse-cycle unit heats with about the same efficiency (COP) as it cools, so you can use the same calculation with the heating capacity. That also makes it about a third of the cost of a plug-in resistance heater, which delivers just 1 kW of heat per kW of electricity.

Set the thermostat moderately — each degree of extra cooling adds roughly 5–10% to consumption. Keep filters clean and the outdoor unit shaded and unobstructed, seal the room, and size the unit correctly: an undersized unit runs flat out all day, while a well-sized inverter unit throttles back once the room is at temperature.