Appliance Energy Use Calculator
Our sustainable living calculator computes appliance energy use accurately. Enter measurements for results with formulas and error analysis.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
kWh = Watts × Hours × Days / 1000 | Cost = kWh × Rate
Convert watts to kilowatt-hours by dividing by 1000 and multiplying by usage time.
Worked Examples
Example 1: Space heater
Problem:1500W, 4 hrs/day, $0.12/kWh
Solution:1500×4×30/1000 = 180 kWh × $0.12 = $21.60/mo
Result:$21.60/month
Frequently Asked Questions
How are energy efficiency ratings calculated?
Energy efficiency ratings compare useful output to total input. EER for air conditioners = BTU cooling / watts consumed. SEER is the seasonal average. Energy Star appliances meet strict efficiency criteria. HERS index rates homes where 100 is standard and lower is more efficient. A score of 0 means net-zero energy.
How is wind energy potential calculated?
Wind power is proportional to the cube of wind speed: P = 0.5 * rho * A * v^3, where rho is air density (1.225 kg/m^3), A is rotor swept area, and v is wind speed. Doubling wind speed increases power eightfold. Capacity factor (actual output vs rated capacity) typically ranges from 25-45% for modern turbines.
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy