Compare heat, like for like

Heat pump running cost calculator

Compare the energy cost of delivering the same amount of heat with a gas boiler and a heat pump. Your tariff and the system’s seasonal efficiency drive the answer.

No email requiredYour numbers, visible assumptionsResults stay in your browser

Make it your scenario

The starting values are examples. Replace them with your bills or installation proposal.

Annual useful heat demand · kWh

Heat delivered to rooms and hot water. This is not the same as gas on your bill.

Electricity unit rate · p/kWh

For a time-of-use tariff, use a realistic weighted average.

Gas unit rate · p/kWh

Use your actual unit rate.

Heat pump seasonal efficiency · SCOP

Use the designer’s estimate for your flow temperature and property.

Boiler seasonal efficiency · %

An assumption about the existing system.

Put the result in context

Read the heating cost comparison

Read the guide ↗

The working, made visible

How this tool works

Heat pump electricity = useful heat ÷ SCOP. Boiler gas = useful heat ÷ boiler efficiency. Multiply each by its unit rate. The break-even SCOP compares energy costs only.

What to allow for

This excludes standing charges, servicing, installation, finance and grants. You only avoid a gas standing charge if the gas account can actually close. A room-by-room heat-loss calculation is needed to size a heat pump.

Energy Saving Trust: air source heat pumps ↗