Quick AC Running Cost Calculator

How much does an air conditioner cost to run?

Air conditioner running costs depend on three things: the unit's cooling capacity, its efficiency rating (EER or COP), and your local electricity price. The formula is straightforward: divide cooling capacity (kW) by the efficiency rating to get estimated electrical power draw, then multiply by your rate and hours of use.

Cooling capacity and efficiency

A 3.5 kW split system with an EER of 3.0 draws around 1.17 kW of electrical power while running. The same unit with an EER of 4.5 draws only 0.78 kW — 33% less electricity for the same cooling output. When buying a new AC, comparing EER ratings is the fastest way to estimate long-term running cost differences.

kW vs BTU/h

Cooling capacity is measured in kilowatts (kW) in most countries, and in British Thermal Units per hour (BTU/h) in the US and some other markets. To convert: 1 kW of cooling = approximately 3,412 BTU/h. A common 12,000 BTU/h unit equals roughly 3.5 kW. The toggle above handles this conversion automatically.

Inverter vs fixed-speed units

Fixed-speed air conditioners run at full capacity until the target temperature is reached, then switch off. Inverter units modulate compressor speed continuously to maintain temperature with less cycling. Inverter ACs are typically 20 to 40% more efficient in real-world use, especially during long continuous operation. If you run your AC for extended periods, an inverter unit will deliver a noticeably lower electricity bill over a season.

Comparing your AC costs against total home electricity use? Try the Electricity Cost Calculator or the HVAC Running Cost Calculator.