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Electrical and Energy

Appliance Energy Cost Calculator

Estimate how much an appliance costs to run using its wattage, schedule, duty cycle, standby consumption, quantity, and your electricity price per kWh.

Instant cost projection Daily to annual totals Optional carbon estimate

Enter appliance details

Use measured average power where possible for the most realistic estimate.

Quick appliance presets Editable after selection
Use average measured watts when the load varies.
units
hours
days
100%
Use 100% for a constant load. A refrigerator or compressor may draw rated power for only part of its scheduled time.
W
Enter 0 if the appliance is fully disconnected when not active.
£ /kWh
kg/kWh
Replace the default with a factor appropriate to your electricity supply.

How the appliance energy cost calculator works

The calculator converts appliance power into kilowatt-hours and applies your electricity rate. It separately estimates active operation and standby consumption, which makes it more useful than a basic watts-times-hours calculation.

Enter power Use the appliance rating plate or, preferably, an average measured wattage.
Add the schedule Enter daily hours, weekly days, quantity, and duty cycle.
Enter your tariff Use the energy charge shown on your electricity bill in cost per kWh.
Review projections Compare daily, weekly, monthly, and annual energy use and cost.
Active energy Rated power multiplied by scheduled hours, duty cycle, and appliance quantity.
Standby energy Standby watts applied during the remaining hours of the week.
Average month Monthly figures use the average calendar year rather than assuming every month has 30 days.

Appliance electricity cost formulas

Electricity suppliers bill energy in kilowatt-hours. One kilowatt-hour is the energy used by a 1,000-watt load operating for one hour.

Active energy per week kWh = (W ÷ 1000) × hours/day × days/week × duty cycle × quantity
Standby energy per week kWh = (standby W ÷ 1000) × standby hours/week × quantity
Electricity cost Cost = total energy in kWh × tariff per kWh
Measured power improves accuracy A nameplate may show maximum input rather than typical consumption. A plug-in energy meter or smart plug can reveal the real average power and cycling behaviour.

Typical appliance examples

The following figures are illustrative only. Actual power varies by model, size, settings, efficiency, temperature, and operating condition. Use your appliance label or measured value whenever available.

Appliance Illustrative power Example schedule Duty cycle Standby
LED bulb10 W6 h/day, 7 days100%0 W
Laptop65 W6 h/day, 7 days100%1 W
Television120 W5 h/day, 7 days100%0.5 W
Refrigerator150 W24 h/day, 7 days35%0 W
Washing machine500 W1 h/day, 4 days100%0.5 W
Air conditioner1,500 W8 h/day, 7 days70%2 W
Electric heater2,000 W5 h/day, 7 days80%0 W
Electric kettle2,200 W0.2 h/day, 7 days100%0 W

How to reduce appliance running costs

Cost reduction usually comes from lowering power, shortening operating time, reducing unnecessary standby consumption, or using the appliance more efficiently.

Cut avoidable standby loadsSwitch off or unplug devices that do not need to remain connected.
Optimise temperature settingsHeating, cooling, refrigeration, and water heating can be sensitive to set points.
Maintain equipmentClean filters, ventilation paths, coils, seals, and moving components as recommended.
Compare energy labelsConsider annual energy use, capacity, and expected usage—not wattage alone—when buying.
Use timers and controlsSchedules, occupancy sensors, smart thermostats, and sleep settings can reduce waste.
Measure before replacingConfirm which appliances are actually responsible for the largest energy use.

Frequently asked questions

How do I calculate the electricity cost of an appliance?

Convert watts to kilowatts by dividing by 1,000. Multiply by operating hours and quantity to obtain kWh, then multiply the energy by your electricity price per kWh. This calculator also includes duty cycle and standby power.

What does duty cycle mean?

Duty cycle is the percentage of scheduled time during which the appliance draws approximately its entered active power. Use 100% for a steady load. A refrigerator, pump, compressor, or thermostatically controlled heater may have a lower average duty cycle.

Should I enter input power or output power?

Use electrical input power because that is what the energy meter records. Mechanical output, cooling capacity, heating output, horsepower, and other performance ratings are not necessarily the same as electrical input.

Does standby power apply during unused days?

Yes. The calculator assumes the appliance remains plugged in and draws the entered standby watts whenever it is outside the scheduled active-use period. Enter zero standby power when the appliance is fully disconnected or truly consumes nothing while idle.

Why does my electricity bill differ from this estimate?

Your bill may include standing charges, taxes, tariff tiers, time-of-use rates, demand charges, seasonal changes, and many other appliances. Actual appliance power can also vary significantly during operation.

Can I use this calculator for a refrigerator or air conditioner?

Yes, but cycling loads require a realistic duty cycle or measured average consumption. For the best estimate, use an energy meter over several representative days rather than relying only on compressor nameplate power.

What carbon factor should I enter?

Use a current emissions factor that matches your electricity grid, supplier, or renewable-energy accounting method. The default is only a generic placeholder and should be replaced when carbon accuracy matters.

Estimate, not a utility bill Results depend entirely on the entered assumptions. For high-value decisions, measure actual energy use and verify your tariff details directly from the latest bill or supplier documentation.