Understanding your result
The period total combines running energy and standby energy during the rest of each day. Cost is expressed in the same currency units as the rate entered. Fixed bill charges are not allocated to this appliance.
To estimate backup duration for the same load, use the Battery Runtime Calculator with battery capacity and conversion losses.
The formula
Watts describe power; hours turn that power into energy. Adding the two operating states gives total kilowatt-hours. Multiplying by the tariff per kilowatt-hour produces the variable electricity cost for the selected period.
Worked example
A device averaging 1,000 W for two hours daily uses 60 kWh in thirty days. At 2 W standby for the other twenty-two hours, it adds 1.32 kWh. At 0.20 per kWh, the combined cost is 12.264 currency units.
How to use this calculator
- Enter measured average running watts and daily operating hours.
- Enter standby watts, or zero if disconnected outside operating hours.
- Set the period and the variable price from your electricity bill.
Average power versus nameplate power
A rated wattage can describe a maximum rather than average draw. Thermostats, motors, brightness settings, and operating cycles can change consumption. If a meter measures a complete representative cycle, divide its watt-hours by the cycle hours to obtain average watts. Avoid applying another duty-cycle reduction when the entered power already averages those pauses.
Using electricity tariffs consistently
Enter a price in currency units per kWh: twenty cents is 0.20 when the currency unit is a dollar. Time-of-use prices require separate calculations for periods at different rates. Standing charges, demand charges, tier transitions, and taxes are excluded unless deliberately incorporated in an appropriate effective unit rate.
Assumptions & limitations
What this calculation assumes
- The same running and standby schedule repeats every day.
What to keep in mind
- Does not automatically identify an appliance’s real power draw or tariff.
Common questions
Can I set standby power to zero?
Yes. Do that when the device is unplugged or its off-state draw is negligible for the estimate.
How do I handle a refrigerator?
Use measured average power over a representative period, or enter actual compressor-running hours with the relevant power. Do not assume the rated compressor draw continues all day.