Thinking about switching to an air source heat pump, or already have one and want to check the numbers? This calculator gives you a realistic estimate of what a heat pump costs to run in a UK home — and how that compares with staying on gas, oil, LPG or electric resistance. Enter a few details about your property and energy prices, and you get an annual figure you can plan around.
Heat pump running costs are widely misunderstood. Because electricity costs more per unit than gas, it is easy to assume a heat pump must be expensive to run. In practice a well-installed heat pump turns each unit of electricity into three or four units of heat, which closes most of that gap — and on the right tariff it can undercut a gas boiler. The calculator above shows where your own home is likely to land.
How we work out your heat pump running costs
The method is the same simple industry relationship used by Nesta, the Energy Saving Trust and Which?: take your home’s annual heat demand (kWh for heating and hot water), divide by the heat pump’s SCOP, then multiply by your electricity unit rate.
A typical three-bedroom UK home needs somewhere in the region of 11,000–12,000 kWh of heat a year, though a well-insulated new-build can be far lower and a large, draughty period property much higher. Nesta’s MCS-derived archetypes sit behind the property-type defaults: about 5,800 kWh for a flat, 11,600 for a terrace or semi, and 18,300 for a detached house.
At a heat demand of 12,000 kWh and a SCOP of 3.3 (the 1980–2010 mid-band default in the calculator), the heat pump uses roughly 3,640 kWh of electricity a year. At the Ofgem price-cap electricity rate of 26.11p/kWh (July–September 2026 Direct Debit average — time-sensitive), that works out at around £949 a year of heating electricity. Electricity standing is excluded from the heating comparison because every home pays it; the calculator shows it as a separate budgeting line. Change insulation, SCOP or tariff and the figure moves.
What affects your heat pump running costs
Three things drive the number more than anything else: how much heat your home needs, how efficiently the heat pump delivers it, and what you pay for electricity.
Your home’s heat demand and insulation
The less heat your home loses, the less your heat pump has to work. Loft and cavity wall insulation, draught-proofing and double glazing all cut annual heat demand. Insulation matters twice with a heat pump: a warm, well-sealed home lets the system run at lower flow temperatures, where it is most efficient. A poorly insulated home forces higher flow temperatures and hurts SCOP.
The heat pump’s efficiency (SCOP)
SCOP is the single biggest lever after heat demand. A system at SCOP 4.0 uses noticeably less electricity than one at 2.8 for the same heat output. Efficiency depends on the equipment and heavily on the installation — correct sizing, well-matched radiators or underfloor heating, and a low flow temperature all lift real-world SCOP. That is why a good installer matters as much as the badge on the outdoor unit.
Your electricity tariff
On a standard variable tariff at the price cap, a heat pump is competitive with gas. On a dedicated heat-pump or time-of-use tariff — cheaper off-peak electricity — running costs can fall well below a gas boiler. Use the Advanced specialist-tariff field to test a blended rate if you have one.
Heat pump vs gas, oil, LPG and electric
At current price-cap rates (electricity 26.11p/kWh, gas 7.33p/kWh — July–September 2026), a typical 3-bed at SCOP 3.3 is usually cheaper than an 85% gas boiler on heating electricity alone — about £86/year if you keep a gas connection for cooking, or closer to £192/year if you leave the gas grid (gas standing then stays on the gas home only). Raise SCOP further and the gap widens.
Oil and LPG are not on the Ofgem cap. Defaults here use DESNZ standard-grade burning oil (June 2026) converted to p/kWh, and a published UK LPG litre benchmark converted with a propane net calorific factor. Both are editable — your delivery quote matters more than any national average. Electric resistance at ~100% efficiency makes the heat pump look dramatically cheaper; that is honest physics, not a trick, but caption it when you share the result.
What is SCOP, and why it matters
SCOP stands for Seasonal Coefficient of Performance. A SCOP of 3.5 means that, averaged across a full year including cold winter days, the heat pump produces 3.5 kWh of heat for every 1 kWh of electricity it draws. A gas, oil or LPG boiler is always less than 100% efficient — it can never turn one unit of fuel energy into more than one unit of heat.
That multiplier is why heat pumps stay affordable despite electricity costing more per unit than gas. Most modern air source heat pumps are rated between SCOP 3.0 and 4.0. The real-world figure depends on design, sizing and setup, which is why the same unit can perform very differently in two homes. The calculator shows a SCOP ±0.5 band so you see that uncertainty instead of a false precision.
How to cut your heat pump running costs
Start with the tariff: a dedicated heat-pump or time-of-use electricity tariff is usually the fastest saving. Run the system low and steady at a lower flow temperature rather than blasting heat in short bursts. Make sure emitters are large enough (see the radiator BTU calculator) or move to underfloor heating. Improve insulation. Keep the unit maintained.
If you are installing, the Boiler Upgrade Scheme offers a £7,500 grant towards an air source heat pump in England and Wales (confirm current status and end date on GOV.UK — currently flagged through March 2027). That is a capital subsidy. It does not change running cost, so it is deliberately kept out of this calculator’s maths.
Frequently asked questions
How much does an air source heat pump cost to run per year?
For a typical three-bedroom UK home, an air source heat pump often costs roughly £850–£1,050 a year on a standard tariff, depending on heat demand, SCOP and your electricity price. Better-insulated homes and specialist tariffs sit lower. Use the calculator for your own inputs.
How much does a heat pump cost to run per month?
Spread evenly, £850–£1,050 a year is about £70–£88 a month. In reality costs weight toward winter.
Are heat pumps cheaper to run than gas boilers?
They can be. SCOP 3.5 or above is competitive with gas on the price cap and clearly cheaper on a specialist tariff. Poor insulation or a low SCOP can reverse that.
What is a good SCOP for a heat pump?
Most modern air source heat pumps achieve SCOP between 3.0 and 4.0. Around 3.5 or higher is a strong real-world result. Installation quality and home fabric matter as much as the unit.
Will a heat pump work in a poorly insulated home?
Yes, but it will cost more to run and may struggle to achieve a high SCOP. Improve insulation alongside or before installation where you can.
Is there a grant to help with the cost of a heat pump?
Yes — the Boiler Upgrade Scheme (£7,500 for air source, England and Wales). Confirm current status on GOV.UK. It cuts upfront cost, not the running-cost figure on this page.
How accurate is this calculator?
It is a sense-checkable estimate from heat demand, SCOP and unit prices with dated UK sources. Your actual bills depend on design, install and how you run the system — treat the result as a guide, not a quote.
When to call a professional
This tool estimates running cost. It does not size a heat pump, design emitters, or replace an MCS-certified design survey. If you are deciding whether to switch, use the result to stress-test SCOP and tariff assumptions, then speak to a qualified installer with your EPC and real consumption figures.
Related on CalcLab: the Radiator BTU calculator for emitter output at lower flow temperatures. Boiler size and ASHP sizing tools are next in the heating cluster.