Heat Pump COP & Running Cost
Calculate a heat pump's coefficient of performance (COP), its Carnot limit and the running cost compared with resistive heating, free online.
About this calculator
COP = heat delivered ÷ electricity used. The theoretical (Carnot) maximum for heating is T_hot ÷ (T_hot − T_cold) in kelvin; real heat pumps reach about 40–55% of it. A COP of 3.5 means each kWh of electricity delivers 3.5 kWh of heat, so the heat costs a third of resistive heating.