Separate input from output
Rated electrical input is measured in watts or kilowatts and belongs in the cost formula. Cooling output in BTU/h or kW describes capacity; substituting it as electricity use can substantially misstate cost.
Electricity calculator
Estimate air-conditioner running costs
Use your appliance power input, electricity tariff and realistic usage pattern. No national “live price” is assumed.
A 1,000 W unit at 25p/kWh
These are maximum-input illustrations, not a live tariff or a promise of actual consumption. Change the calculator to match the exact model and your bill.
| Use | Energy | Cost |
|---|---|---|
| 1 hour | 1.0 kWh | £0.25 |
| 4 hours | 4.0 kWh | £1.00 |
| 8 hours | 8.0 kWh | £2.00 |
The core formula
Cost = power in kW × usage hours × electricity tariff in GBP per kWh. An optional duty cycle can model compressor cycling, but it remains an estimate.
Preserve every input behind the pounds figure
A useful running-cost result can be reproduced from the power input, hours, tariff and duty assumption. If one of those changes, create a new scenario rather than silently replacing the old one.
Use dated tariff evidence
Copy the applicable unit rate from the household tariff and note its date. A national benchmark can illustrate a scenario but should not overwrite a saved calculation based on an actual contract.
Show cycling as an assumption
Inverter control, thermostat setting, room heat gain and exhaust setup can change compressor operation. Present full input and one or more explicit duty-cycle cases instead of calling a lower figure the real cost.
Limit: The calculator excludes purchase, maintenance, standing charges and performance degradation unless entered elsewhere. It does not predict a bill or guarantee compressor behaviour.
Running-cost questions
How do I calculate air-conditioner running cost?
Divide electrical input watts by 1,000, multiply by hours, then multiply by the electricity unit rate in pounds per kWh. Use input watts, not the BTU/h cooling-output figure.
How much does a 1,000 W air conditioner cost for eight hours?
At the editable round example of 25p/kWh, eight hours at continuous 1,000 W input uses 8 kWh and costs £2.00. Actual compressor use can cycle and your tariff may differ.
Is the calculator showing a live national tariff?
No. The 25p/kWh starting value is a round planning example. Replace it with the dated unit rate on your own tariff.
Continue with evidence
Your next checks
Move from the current answer to sizing, evidence and a clear commercial next step.
PARENT TOPICAir-conditioner running costsKeep tariff assumptions and model evidence visible.DECISION TOOLCheck the capacity requirementCost is not useful if the selected unit is wrong for the room.DECISION TOOLModel an overnight scenarioTest full-input and explicit cycling cases without a savings promise.GUIDEUnderstand the calculationLearn which wattage and tariff figures belong in the formula.GUIDEAvoid false economy from poor sizingRoom conditions determine the capacity band before watts are compared.NEXT ACTIONCompare verified rated inputSee source-backed model data on one comparable basis.