Heat Pump Savings Calculator
What a heat pump would save on heating each year, and how long it takes to pay back.
Good to know. A heat pump moves heat instead of making it, so one kWh of electricity can deliver three of warmth.
Approximate. Real-world values vary.
How it works
In plain words
Your bill divided by the fuel price is the fuel you buy; times the boiler’s efficiency, it is the heat your home uses. A heat pump delivers that heat using the heat divided by its SCOP in electricity.
The formula
heat = (bill ÷ fuel price) × efficiency heat pump electricity = heat ÷ SCOP saving = bill − electricity × price payback = installation ÷ saving
Worked example
1,440 of fuel at 0.12 a kWh is 12,000 kWh, or 10,800 kWh of heat at 90% efficiency. A heat pump with a SCOP of 3.2 needs 3,375 kWh of electricity, 843.75 at 0.25: a saving of 596.25 a year, paying back 12,000 in about 20 years.
Sources
- NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B One therm is 100,000 Btu, or about 29.3 kWh.
Sources checked October 3, 2026. 3 automated tests check its answers on every change.
About the heat pump savings calculator
A gas or oil boiler burns fuel to make heat, and a good one turns about 90% of the fuel into warmth. A heat pump uses electricity to move heat from the outside air, the ground or water into the house, so it delivers several times more heat than the electricity it uses. Over a year that ratio is the SCOP, typically 2.5 to 4.
Whether that saves money depends mostly on prices. Electricity costs more per kWh than gas almost everywhere, so a heat pump wins when its SCOP is higher than the ratio between the two prices. The last result shows the electricity price at which both cost the same: below it the heat pump is cheaper to run.
The SCOP depends on the house as much as the machine. Well-insulated homes with large radiators or underfloor heating can run at low water temperatures, which is where heat pumps are most efficient. Replacing oil, propane or electric heaters usually saves the most.
Payback includes only running costs. Grants, a boiler that needs replacing anyway, lower maintenance and a separate cheaper electricity tariff all change the picture; enter the installation cost after grants. For solar panels, use the solar payback calculator.
Questions people ask
Is a heat pump cheaper to run than gas?
When its SCOP is higher than electricity’s price divided by gas’s. At 0.25 and 0.12 a kWh, that is above about 2.1 for a 100% efficient boiler, or 1.9 for a 90% one.
What is SCOP?
The seasonal coefficient of performance: heat delivered divided by electricity used over a whole heating season. A SCOP of 3 gives 3 kWh of heat for 1 kWh of electricity.
How do I convert a price per therm to kWh?
Divide by 29.3. One therm is 29.3 kWh, so 1.50 a therm is about 0.051 a kWh.