Electricity Cost Calculator: What an Appliance Really Costs to Run
Running cost is power in kilowatts × hours used × price per kilowatt-hour. This calculator turns an appliance's wattage and daily usage into a cost per day, month and year, which is the honest way to compare an old appliance against a replacement.
Finding the wattage
The rating plate on the appliance, or the manual, gives watts or amps. If only amps are listed, multiply by the supply voltage to get watts. Divide watts by 1,000 to get kilowatts. A 2,000 W heater is 2 kW, so four hours a day at 0.30 per kWh costs 2 × 4 × 0.30 = 2.40 daily, or around 876 a year.
The biggest household consumers
- Electric heating, immersion heaters and electric showers — by far the largest loads.
- Tumble dryers, ovens and kettles — high power, moderate hours.
- Fridges and freezers — low power but running 24 hours a day.
- Standby loads across a house typically add 5-10% to a bill.
Rated versus actual consumption
Thermostatically controlled devices cycle on and off, so a 2 kW heater does not draw 2 kW continuously. Fridges, air conditioners and freezers behave the same way. A plug-in energy monitor measures true consumption over a week and gives a far more accurate figure than the rating plate for anything with a thermostat or variable load.
Key takeaways — Electricity Cost Calculator
- Cost = (watts ÷ 1000) × hours × price per kWh.
- Check whether your tariff has separate day and night rates or standing charges.
- Measure cycling appliances with a plug-in monitor instead of trusting the rating plate.