Electricity Cost Calculator: Estimate Appliance Running Costs

How to use the electricity cost calculator

1. Find the wattage of your appliance on its label, power brick or user manual.
2. Estimate how many hours per day the device runs at that wattage.
3. Look up your electricity rate on your utility bill, usually listed in cents per kilowatt-hour (kWh).
4. Enter all three values into the fields above to see the daily, monthly and yearly running cost.

How the calculation works

The electricity cost calculator uses a single formula applied across three time periods. First it converts watts to kilowatts by dividing by 1,000, then multiplies by hours and by the rate.

Daily kWh = Watts / 1000 x Hours per day

Daily cost = Daily kWh x Rate per kWh

For example, a 1,500 W space heater running 6 hours a day at 16 cents per kWh:

• 1,500 / 1,000 = 1.5 kW
• 1.5 kW x 6 h = 9 kWh per day
• 9 kWh x $0.16 = $1.44 per day

Monthly cost assumes 30 days and yearly cost assumes 365 days. The tool rounds currency to two decimal places using standard half-up rounding.

Typical appliance wattages

Use this reference table to estimate the power draw of common household devices when checking labels is not practical. Actual consumption varies by model, age and settings.

Devices with compressors or heating elements cycle on and off, so their average draw over an hour is lower than the peak rating printed on the nameplate.

Finding your electricity rate

Your rate appears on your monthly utility bill, often listed as "price per kWh" or broken into supply and delivery charges. Add all per-kWh charges together for the most accurate number. In the United States the residential average was about 16 cents per kWh in 2023, but rates range from under 10 cents in some states to over 30 cents in others.

If you are on a time-of-use plan, you may have separate peak and off-peak rates. Run the electricity cost calculator twice, once for each rate, to see the difference. For solar panel owners who export power, use your net rate after any feed-in tariff credits.

Common mistakes to avoid

A frequent error is entering the full 24 hours for appliances that cycle, such as refrigerators or air conditioners. A fridge rated at 150 W does not run its compressor constantly. Its actual daily energy use might be only 1 to 2 kWh rather than 3.6 kWh. Check the EnergyGuide label or your smart meter data for real-world figures.

Another mistake is confusing volt-amperes (VA) with watts. Many UPS units and power supplies list VA ratings, which include reactive power. The actual wattage consumed is lower. Look for the "W" figure specifically.

Finally, remember that standby power adds up. Devices left plugged in, like televisions, chargers and game consoles, can draw 1 to 10 W continuously. While small individually, several devices on standby around the house can cost a noticeable amount over a year.

Reducing your energy costs

Once you know which appliances cost the most, you can target them for savings. Replacing incandescent bulbs with LEDs cuts lighting costs by roughly 80 percent. Upgrading an old refrigerator to an Energy Star model often pays for itself within a few years through lower power consumption.

For heating and cooling, improving insulation and sealing drafts reduces the runtime of space heaters and air conditioners. Smart plugs with built-in energy monitoring let you verify the numbers this calculator produces against real measurements. If you also want to estimate travel expenses alongside home energy spending, a fuel cost calculator handles vehicle fuel budgets.

Worked examples

Each result below was produced by the same code the tool runs, so you can check your own numbers against them.