Skip to content
CalculatorBuddy

Electricity Calculator

Estimate an appliance's electricity use and cost per day, week, month, and year from its power, duty cycle, usage, and electricity price.

Maintained by CalculatorBuddy TeamEditorial methodology

Add as a preferred source on Google (opens in a new tab)

ExampleSample values — edit any field to see your result.

Choose a preset or define your own values below.

%

Average percentage of rated power used while the appliance is operating.

$ per kWh

Results update as you type.

Electricity usage per day

24.000kWh

Estimated result

Cost per day
$3.60

Saved calculations stay only in this browser. Share copies a link containing your entered values.

Compare scenarios

Keep a baseline, then change an assumption to see its effect side by side.

Usage and cost by time span

Time spanElectricity usageCost
per day24.00$3.60
per week168.00$25.20
per month730.50$109.58
per year8,766.00$1,314.90
Electricity usage per day24.000 kWh
Estimate the energy and cost of an appliance over a day, week, month, and year. Choose a common appliance or enter its rated power, typical capacity, operating time, and your utility price.

How to use this calculator

Enter the appliance’s power and the time it actually runs, then apply your tariff per unit of energy. Convert watts to kilowatts where required. The estimate covers the entered usage; fixed charges and other bill components need to be added separately.

Examples

1,000 W continuously

At 100% capacity for 24 hours, the appliance uses 24 kWh/day, 730.5 kWh/month, and 8,766 kWh/year. At $0.15/kWh that is $3.60/day and $1,314.90/year.

Formula

daily kWh = watts ÷ 1,000 × hours per day × capacity ÷ 100

cost = kWh × price per kWh

Power units are converted to watts first. A BTU/hour is 0.293071 watts, one metric horsepower is 735.49875 watts, and one refrigeration ton is 3,516.853 watts.

Use the energy label or a plug-in power meter when possible. Nameplate wattage is often a maximum, especially for heating, cooling, and motor loads.

Assumptions and limits

Preset wattages and duty cycles are editable examples, not measurements of a specific appliance. Standby power, startup current, thermostat behavior, variable-speed operation, defrost cycles, seasonal use, and time-varying rates can change the bill. The month is one twelfth of 365.25 days. Enter the full price per kWh that applies to the usage being modeled; fixed customer charges, demand charges, taxes, tier boundaries, and credits are outside the result.

The US Department of Energy's home energy teaching material illustrates why appliance wattage and operating hours should be treated as inputs rather than universal constants. A device label or measured kWh is the better source for an individual appliance.

Frequently asked questions

How do I calculate electricity cost?
Multiply rated kilowatts by operating hours and duty cycle to get kWh, then multiply kWh by your electricity price.
Why does an appliance use less than its rated wattage?
Thermostats and variable-speed controls cycle equipment, so the capacity percentage estimates its average load while scheduled to run.
How is a month calculated?
Monthly estimates use one twelfth of 365.25 days, or 30.4375 days.

Related calculators