Electricity Cost Calculator
Estimate the running cost of an appliance.
Find out how much an appliance costs to run over a period.
How the Math Works
The Electricity Cost Calculator uses the fundamental relationship between power, energy, and cost. First, it converts the appliance's wattage (W) to kilowatts by dividing by 1000, since electricity is billed per kilowatt-hour (kWh). The energy consumption in kWh is then calculated by multiplying the power in kilowatts by the number of hours the appliance runs each day and the number of days of usage. Finally, the total cost is determined by multiplying the energy consumption (kWh) by the electricity rate per kWh. This straightforward formula: kWh = (W ÷ 1000) × hours × days, followed by cost = kWh × price, provides an accurate estimate of operating expenses.
Practical Applications
To use this calculator, simply enter the appliance's wattage (found on its label or manual), the number of hours you use it daily, the number of days you use it, and your electricity rate per kWh (available on your utility bill). For example, a 1200W microwave used for 0.5 hours daily over 30 days at $0.12 per kWh would consume (1200 ÷ 1000) × 0.5 × 30 = 18 kWh, costing 18 × $0.12 = $2.16 per month. The calculator automates these calculations, allowing you to quickly compare different appliances or usage patterns without manual computation.
Day-to-Day Use
This calculator empowers you to make informed decisions about your energy consumption and budget. By understanding exactly how much each appliance costs to run, you can identify energy guzzlers and adjust your habits—like running the dishwasher only when full or using a programmable thermostat to reduce heating costs during unused hours. It's especially valuable for household budgeting, helping you anticipate monthly utility expenses and plan for energy-saving upgrades. Whether you're comparing appliance models before purchase or simply trying to reduce your carbon footprint and electric bill, this tool transforms abstract power ratings into concrete, actionable cost information.
Worked example
1,000 W for 3 h/day over 30 days at $0.15/kWh → 90 kWh × 0.15 = $13.50.
FAQ
Where do I find an appliance's watts?
On its label/nameplate, or estimate from its amps × volts.