What is COP on a heat pump?

Updated 29 September 2026

Short answer: COP (coefficient of performance) is heat out divided by electricity in. A COP of 3 means you get 3 kWh of heat for every 1 kWh of electricity you pay for.

A heat pump doesn't make heat from electricity the way a kettle does. It uses electricity to move heat from the outside air into your home, which is why it can give out more than it takes in. COP is the measure of how much more.

COP isn't fixed. It moves with the weather, the time of day and whether it's heating the house or the hot water, so a COP for one day or one hour is only part of the story. A week or a month, set against the weather, tells you much more. You may also see SCOP (seasonal COP), the figure averaged over a whole year.

In Snugdays: Avg COP is total heat out divided by total electricity in for the period, not an average of hourly figures, so the numbers always add up.