Air Conditioner Running Cost Calculator
Estimate how much your air conditioner costs to run per hour, day, month and cooling season. Add your unit power, efficiency, electricity tariff, daily usage pattern and optional standby power to get a realistic cost estimate.
Calculator
Use “known electrical power” if your AC label already gives watts/kW. Use “cooling output + efficiency” if you know BTU, EER, SEER or COP.
Presets give realistic starting values only. Replace them with your unit’s rating plate details where possible.
Unit rate in pence per kWh.
The actual input power used by the AC.
Usually advertised as BTU/h or kW cooling.
12,000 BTU/h is about 3.52 kW of cooling output.
EER/SEER are common on cooling equipment; COP is common in engineering specs.
Typical portable/window AC values are often around 8–12 EER.
This is the estimated kW the unit draws from the wall before usage pattern and compressor cycling are applied.
AC units cycle on/off once the room is near set temperature.
How many hours the AC is switched on per day.
For a typical month estimate.
Useful for summer/annual budgeting.
Optional: power used when plugged in but not cooling.
Estimated grid emissions per kWh.
Efficiency comparison
Compare your current unit against a more efficient AC to estimate potential savings.
Estimated running cost
Energy breakdown
—Savings scenario
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How the calculation works
Air conditioner running cost is mainly based on electrical energy use. If you know the electrical input power, the calculator uses it directly:
If you only know cooling output and efficiency, the calculator estimates electrical power. For BTU/h and EER, it uses watts = BTU/h ÷ EER. For kW cooling and COP, it uses electrical kW = cooling kW ÷ COP.
Standby energy is added separately when the unit is plugged in but not actively cooling. The monthly and seasonal estimates are therefore a practical budgeting estimate rather than a laboratory test result.
Note: Real AC costs vary with outdoor temperature, insulation, room size, window area, thermostat setting, refrigerant condition, filters, installation quality and how often doors or windows are opened.
Typical AC running cost factors
Power rating
A larger unit usually cools faster but may cost more per hour. A badly oversized unit can short-cycle, while an undersized unit may run constantly.
Efficiency
Higher EER, SEER or COP means more cooling for each unit of electricity. This matters most when the AC is used for long hours.
Thermostat setting
Lower target temperatures increase compressor runtime. Raising the setpoint by a few degrees can noticeably reduce energy use.
Room heat gain
Sun-facing rooms, poor insulation, open windows, appliances and many occupants all increase the cooling load.
How to reduce AC running costs
- •Use a moderate set temperature. Avoid setting the AC much colder than needed; this increases compressor runtime and cost.
- •Close curtains or blinds during peak sun. Reducing solar heat gain means the AC does less work.
- •Seal gaps around windows and doors. Hot outside air entering the room can make a portable or window AC run continuously.
- •Clean filters regularly. Blocked filters reduce airflow and can make the unit less efficient.
- •Use fans with AC. Air movement can make the room feel cooler, allowing a higher thermostat setting.
- •Cool only occupied rooms. Do not waste energy cooling spaces that are not being used.