Calculator
Electricity & Energy Cost Calculator
Calculate energy use and consumption-based electricity costs from power and operating time.
Calculate electricity use
Watts describe power; kilowatt-hours describe energy used over time.
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Complete the visible fields with valid values.
Watts and kilowatts
W and kW measure power. 1 kW is exactly 1,000 W.
Wh and kWh
Wh and kWh measure energy. Energy equals power times time; 1,000 W for one hour is 1 kWh.
Electricity cost
Cost is consumed kWh times your own price per kWh. No live prices or fixed tariff charges are included.
Weekly model and 24/7
Recurring use uses the entered weeks, normally 52. Continuous operation explicitly uses 365 days or 8,760 hours.
Standby
Standby is calculated from its wattage and standby hours just like any other load.
Variable power
Computers, refrigerators and washers often vary their draw. A measured average may be more useful than maximum rated power.
Frequently asked questions
How much does a 100-watt device cost per hour?
100 W for one hour is 0.1 kWh; multiply by your kWh price.
How do I convert watts to kWh?
Multiply watts by hours and divide by 1,000.
What is 1,000 watts for one hour?
Exactly 1,000 Wh or 1 kWh.
What does a kWh cost?
Enter the price from your tariff; no current price is loaded.
How do I calculate annual use?
Multiply power by hours per day, days per week and weeks per year, then divide by 1,000.
What does standby cost?
Standby power times standby time gives energy, which is multiplied by price.
Why can actual use differ?
Many devices regulate power, so rated and average power can differ.
How is the monthly value calculated?
Annual value divided by 12, not weekly value times four.
What does continuous operation mean?
It explicitly uses 24 hours for 365 days.
Can I compare two devices?
Yes. Annual energy and costs are compared under common usage.
Does this calculate solar or batteries?
No. PV, storage and battery runtime are outside this calculator's scope.