Heat pump vs gas boiler running costs come down to two numbers: how much more a kWh of electricity costs than a kWh of gas, and how many kWh of heat your heat pump delivers for each kWh of electricity it uses. When the second number is bigger than the first, adjusted for your boiler's efficiency, the heat pump is cheaper to run. This guide shows the arithmetic with prices you can replace by your own.
In this guide
Start with the cost of one kWh of heat
Neither fuel is what you actually want. You want heat in the rooms, so the fair comparison is the cost per kWh of heat delivered.
A gas boiler turns most of the gas it burns into heat. At 90 percent efficiency, each kWh of heat needs 1.11 kWh of gas. With gas at 0.08 per kWh, one kWh of heat costs 0.089.
A heat pump moves heat instead of making it. With a seasonal coefficient of performance (SCOP) of 3.2, each kWh of electricity delivers 3.2 kWh of heat. With electricity at 0.28 per kWh, one kWh of heat costs 0.0875.
So at these prices the two systems are almost tied, at 0.089 and 0.088. A small change in either price, or a slightly better or worse installation, tips the result.
The price ratio rule
Divide the electricity price by the gas price. In the example that is 0.28 ÷ 0.08, a ratio of 3.5. A heat pump wins when the ratio is below the SCOP divided by the boiler efficiency, which here is 3.2 ÷ 0.90, or 3.56. A ratio of 3.5 sits just under that line, so the heat pump edges ahead.
The same rule can be turned around to give the highest electricity price at which a heat pump still matches gas, with gas at 0.08 and a 90 percent boiler.
| Heat pump SCOP | Highest electricity price per kWh that still matches gas |
|---|---|
| 2.5 | 0.222 |
| 3.0 | 0.267 |
| 3.5 | 0.311 |
| 4.0 | 0.356 |
At a SCOP of 2.5, electricity at 0.28 makes the heat pump dearer to run. At a SCOP of 4.0 it would still win with electricity at 0.35. You can look up the equivalent figures for your own prices with the heat pump vs gas boiler calculator.
What the ratio looks like in real markets
The ratio moves with policy and markets. An installer comparison using the October 2026 UK price cap put electricity at about 3.3 times the price of gas, as Reonic reports from Ofgem figures. Heat Geek noted that the April 2026 price cap moved some policy costs away from electricity bills, which narrows the ratio and favours heat pumps. Other countries have different taxes and levies on each fuel, so the ratio in your country may be higher or lower. Your latest bill is the best source.
Tariffs can matter as much as the machine
A heat pump that draws power at a cheaper off-peak rate has a lower cost per kWh of heat without any change to the equipment. In the calculator example, keeping the SCOP at 3.2 and switching to a heat pump tariff at 0.20 per kWh cuts the yearly running cost from 1,050 to 750 for a home that needs 12,000 kWh of heat. The gas boiler stays at 1,067. The saving rises from 17 to 317 a year.
Not every country or supplier offers a tariff like this, and a time-of-use tariff only helps if a heat pump can shift some of its running into the cheap hours, for example by heating a hot water cylinder overnight. Check what your supplier offers and how the unit rates are structured.
Efficiency swings the result
SCOP is not a fixed property of the machine. It depends on the flow temperature of your heating system, the size of your radiators, the outdoor climate and how well the system was commissioned. A heat pump that delivers 3.8 in one house can deliver 2.6 in another. At 0.28 per kWh and 12,000 kWh of heat, the first costs 884 a year and the second 1,292, against 1,067 for gas. Read the guide on SCOP and heat pump efficiency to see how to ask an installer for a realistic figure.
Running cost is only half of the decision
The upfront cost of a heat pump is higher than a boiler, and the running cost saving rarely closes that gap alone. Payback depends heavily on grants and on whether you would have replaced a boiler anyway. With a 12,000 installation, a 7,500 grant and a 2,500 boiler you would have bought regardless, a 317 yearly saving gives a payback of 6.3 years. Without the grant or the avoided boiler, the same saving needs more than 37 years. Add comfort, quieter operation, no gas connection and the option to add solar, and the picture changes again. The International Energy Agency estimated that heat pumps avoided about 20 billion cubic metres of gas in Europe in 2024 and supplied around 6 percent of heating, according to a Selectra summary of its Heat Pump Monitor.
Steps to run your own comparison
- Find your annual gas use in kWh, converting from cubic metres if needed with the gas conversion guide.
- Multiply by your boiler efficiency to get the heat you use.
- Ask a heat pump installer for the expected SCOP of your home and the installed price, then ask for a lower case as well.
- Enter your gas price, electricity price and any heat pump tariff in the calculator.
- Repeat with a pessimistic SCOP and a cautious electricity price. If the heat pump still looks reasonable, the decision rests on solid ground.
Frequently asked questions
Will a heat pump always cut my energy bill?
No. At today's prices in many countries the result is close, and a poor installation can make the heat pump dearer to run than gas. A tariff designed for heat pumps and a good SCOP make a clear difference.
Does a heat pump work in cold weather?
Yes, though efficiency falls as the outdoor temperature drops. SCOP already averages over the whole heating season, so a realistic SCOP includes the cold days.
Is oil or LPG heating different?
The method is the same. Enter the fuel price per kWh and the boiler efficiency. Oil and LPG are usually more expensive per kWh than mains gas, which favours heat pumps.