Heat Pump vs Gas Calculator
A heat pump delivers three or four units of heat for every unit of electricity, while a gas boiler delivers slightly less than one unit for each unit of gas. Whether that makes it cheaper depends entirely on how much more expensive electricity is than gas where you live.
Your inputs
Your result
Formula
One ratio decides it
A heat pump wins on running cost whenever electricity costs less than SCOP × boiler efficiency times the price of gas. With a SCOP of 3.4 and an 88% boiler, that break-even ratio is about 3.0: electricity can cost three times what gas costs before the boiler becomes cheaper.
The calculation shows both numbers — the ratio where they tie, and the ratio you actually pay. If your ratio is below the break-even one, the pump is cheaper to run. Across much of Europe the ratio sits between 2.5 and 4, which is why the answer differs so much by country.
SCOP is the number to interrogate
A manufacturer's figure is measured under test conditions. What matters is the seasonal average in your house: how cold it gets, and above all what temperature the system runs at. A heat pump feeding underfloor heating at 35 degrees performs far better than the same unit pushing 55 degrees through small radiators sized for a boiler.
This is why the radiators and the insulation usually decide the outcome more than the brand of pump. A poorly matched installation can drop the seasonal figure to 2.5 and turn a clear saving into a loss.
Compare against a new boiler, not against no cost
If the existing boiler is near the end of its life, the honest comparison is the extra over replacing it, not the whole installed cost. That is what the payback here uses, and it shortens the period considerably.
The standing charges do not cancel out
Removing gas entirely also removes the gas standing charge, which is a fixed sum every year regardless of use. Where a household keeps gas for cooking, that saving disappears. This is not modelled here; add it to the annual difference yourself if you are disconnecting.
What else changes
A heat pump also provides cooling in summer on many models, which has value in a warming climate and no equivalent on a boiler. It requires outdoor space and makes some noise. And in several countries the electricity price for heating carries a lower tax rate than ordinary consumption, which shifts the ratio in the pump's favour — worth checking before relying on the standard tariff.
Frequently asked questions
How do I find how much heat I need?
Take your annual gas use in kilowatt-hours from the bill and subtract what hot water and cooking use, roughly 2,000 to 3,000 kWh for a typical household.
What SCOP should I assume?
Around 3.0 to 3.5 for radiators sized appropriately, 4.0 or better with underfloor heating, and closer to 2.5 where the system has to run hot through small radiators.
Why compare against a new boiler?
Because if the old one needs replacing anyway, only the difference in price is a real extra cost. Comparing against zero makes the payback look far worse than it is.
Does this include the gas standing charge?
No. If you disconnect gas entirely you also stop paying its standing charge, which adds to the annual saving. Add that separately.