kWh Calculator
Calculate electricity consumption from an appliance's power and daily usage time.
Appliance details
Estimated energy consumption
EstimateFormula
Daily kWh = Watts × Hours per day ÷ 1,000
Total kWh = Daily kWh × Number of days
This estimate assumes the appliance draws the wattage you enter for the full duration of use. Actual energy consumption may vary with operating conditions and power cycling.
How to use the calculator
Enter the appliance's power in watts, how many hours it is used each day, and the number of days you want to calculate. Results update automatically as you change the inputs.
Assumptions and limitations
The calculator converts watts to kilowatts by dividing by 1,000, then multiplies by hours of use to estimate energy in kWh. It assumes a constant power draw during the entered usage time and does not account for standby power, changing power levels, or cycling behavior.
A free tool from HomeCostify to help homeowners plan Electricity projects.
