Heat pump running costs: calculate your electricity use and bills

Heat pump running costs depend on three things: how much heat your home needs, how efficiently the complete system supplies it, and the electricity prices you pay when it operates. There is no single reliable annual bill for a three-bedroom house.

You can, however, make a useful estimate without guessing. This guide explains the calculation, shows how the answer changes, and helps you compare a proposed installation with your current heating. Checked 29 October 2026. The examples are our calculations, not measured customer bills or current tariff quotations.

What does a heat pump cost to run?

For a home needing 12,000kWh of useful heating and hot water annually, a system delivering three units of heat per unit of electricity would use 4,000kWh. At an assumed electricity price of 25p/kWh, that costs £1,000 for the year, before standing charges, servicing and repairs.

Those inputs are illustrative. A smaller heat requirement, better seasonal performance or lower effective electricity price reduces the result; the reverse increases it. The monthly average would be about £83, but winter spending would be substantially higher than summer spending.

Useful annual heat needed	Seasonal efficiency assumed	Electricity needed	Annual energy cost at 25p/kWh
8,000kWh	3.0	About 2,667kWh	About £667
12,000kWh	3.0	4,000kWh	£1,000
16,000kWh	3.0	About 5,333kWh	About £1,333
20,000kWh	3.0	About 6,667kWh	About £1,667

These are not typical bills by property size. They hold efficiency and price constant to show the effect of heat demand. A proper quotation should explain the demand and performance assumptions for your home.

Calculate your own running cost

Annual electricity use = useful heat required ÷ seasonal system efficiency.

Annual heating energy cost = annual electricity use × electricity unit price.

Use pounds consistently: 25p is £0.25. Do not multiply by 25 and then describe the result as pounds. If your electricity price varies by time, calculate each period separately rather than applying the cheapest rate to everything.

The calculator below uses your chosen assumptions. It is an estimate of heating energy only, not a quotation or system design. Set the heat requirement to cover the demand included in your efficiency assumption: a space-heating-only efficiency should not be applied uncritically to heating and hot water together.

How much difference does efficiency make?

Seasonal efficiency	Electricity for 12,000kWh useful heat	Cost at 25p/kWh	Difference from efficiency 3.0
2.5	4,800kWh	£1,200	£200 more
3.0	4,000kWh	£1,000	Reference
3.5	About 3,429kWh	About £857	About £143 less
4.0	3,000kWh	£750	£250 less

All figures use the same heat requirement and price. The table does not establish that a particular model will achieve any listed efficiency in your house.

Ask whether the prediction includes circulation pumps, controls and backup heating, and how hot-water production is treated. Comparing a compressor-only figure with another system's complete measured consumption produces an unfair result. OpenEnergyMonitor explains the measurements and boundaries.

COP, SCOP and measured seasonal performance

COP describes performance under specified operating conditions. SCOP is a standardised seasonal product metric. An installed system's measured seasonal performance depends on its operating conditions and which heat and electricity inputs are counted.

A favourable brochure COP is not a guaranteed annual household result. Ask the installer for a property-specific estimate and its assumptions, then keep the commissioning details so a later performance review has something concrete to investigate.

How do you estimate your home's heat demand?

If you have a boiler, your annual gas consumption includes conversion losses and may include cooking. It is purchased fuel, not automatically useful heat delivered to rooms and taps.

For example, 15,000kWh of gas used for heating and hot water, at an assumed 90% seasonal boiler efficiency, represents about 13,500kWh of useful heat. That is an approximation, not a measurement of the building's requirement.

Collect at least a full year's consumption where possible, identify estimated readings and account for unusual absences. Tell the designer if you currently underheat rooms: an estimate based on that consumption could understate the energy needed to deliver the comfort you actually want.

The installation design also needs a room-by-room heat-loss assessment. Annual energy use and peak heat loss answer different questions. The former helps estimate kWh across a year; the latter helps determine the capacity needed in cold conditions. See our heat pump sizing guide.

Why do winter electricity bills rise?

Cold weather generally increases the heat required by the building, while the heat pump's operating conditions also change. More purchased electricity during winter is therefore expected; it does not automatically indicate a fault.

Do not multiply the coldest day's consumption by 365. Equally, a mild spring week cannot prove a cheap annual bill. Compare meaningful periods alongside outdoor temperatures, occupancy, indoor temperatures and hot-water use.

For budgeting, use an annual estimate and allow for seasonal variation. A level monthly Direct Debit spreads payments, but it does not mean the equipment consumes the same amount each month. Check actual meter readings and account balance before drawing conclusions from the payment alone.

Illustrative image. The equipment and layout for a particular home must be assessed as part of its design.

Is a heat pump cheaper to run than a gas boiler?

It can be, but electricity's higher unit price means efficiency alone does not settle the comparison. Keep useful heat constant.

At the illustrative 12,000kWh demand, gas at 6p/kWh and 90% boiler efficiency costs about £800. A heat pump at seasonal efficiency 3.0 with electricity at 25p/kWh costs £1,000; at efficiency 4.0 it costs £750.

The energy-only break-even efficiency is electricity price multiplied by boiler efficiency, divided by gas price. With those assumptions it is 3.75. Avoided gas standing charges, servicing, repairs and finance can change the whole-house result.

If you retain gas for cooking or hot water, do not count the full gas standing charge as an avoided cost. Ask your supplier about any disconnection arrangements before including removal costs or savings in the budget.

What about heat-pump tariffs?

Compare the whole household's electricity, not just the heat pump. A tariff can combine attractive cheaper periods with a more expensive peak, and may have particular meter or equipment requirements.

Illustrative consumption	Electricity	Assumed price	Cost
Cheaper periods	2,000kWh	15p/kWh	£300
Other periods	1,500kWh	25p/kWh	£375
Expensive periods	500kWh	40p/kWh	£200
Total	4,000kWh	Weighted average 21.875p/kWh	£875

This invented tariff example costs £875, not £600. The latter would incorrectly price every unit at 15p. Add the rest of your household electricity and the applicable standing charge before comparing offers.

For actual options, compare dated regional quotes with the supplier's published terms. Cosy Octopus and EDF Heat Pump Tracker illustrate different time-of-use structures. Neither is automatically cheapest for every home.

What should a real-bill comparison include?

Before treating an owner's bill as evidence for your own home, look for the period covered, weather, heated area, indoor temperatures, hot-water use, tariff, other electricity and what equipment was measured. A screenshot of a monthly payment provides very little of that context.

Ask whether the comparison is before-and-after measured data or a model. If a household also added insulation, solar panels or a battery, establish which changes contributed to the result. A single household can be a useful case study without being representative.

We have not collected owner bills for this guide. Its tables are reproducible calculations intended to help you test predictions and read real case studies critically.

How to lower costs without losing comfort

Start by checking that the system delivers the agreed room temperatures and that the controls match the commissioned design. Record current settings before changing anything, and adjust one ordinary user control at a time.

Weather compensation can vary heating-water temperature with outdoor conditions. A suitable setting may reduce unnecessary high-temperature operation, but copying another household's curve is not a reliable setup method. Ask your installer to explain the commissioned curve and review it if comfort is poor. Energy Saving Trust's controls guidance explains the principle.

Avoid switching off frost protection, safety functions or required hot-water hygiene routines to chase a cheaper bill. If backup heating appears to run frequently, record the circumstances and ask the installer to investigate rather than disconnecting it.

Consider appropriate heat-loss improvements and clear obstructions around emitters or outdoor equipment. Check filters and routine maintenance only as your owner's manual permits. See our servicing guide.

Running-cost FAQs

How much electricity does a heat pump use per day?

There is no useful universal daily figure. The illustrative 4,000kWh annual example averages about 11kWh a day, but actual winter and summer use would differ greatly.

Does leaving a heat pump on always save money?

No single schedule suits every building, tariff and control strategy. Distinguish leaving the system available from forcing it to produce heat constantly. Ask for the intended schedule and compare comfort and consumption over meaningful periods.

Why is my electricity bill higher after installation?

The heat pump has moved heating demand onto electricity. Compare the combined old fuel and electricity cost with the new total, rather than expecting the electricity bill alone to fall.

Should I buy a separate meter?

A dedicated electricity meter can help distinguish heating from other demand. Measuring efficiency also requires reliable heat-output measurement and suitable boundaries. Discuss monitoring options before paying for equipment.

Do solar panels make heating free?

Only the generation available when needed can directly displace imported electricity, unless stored. Account for winter generation and any export payment forgone. Annual solar production is not a promise of winter self-sufficiency.

What should I request with a quotation?

Ask for annual heat demand, proposed system efficiency, predicted electricity use, tariff assumptions, included auxiliary loads and a sensitivity calculation. Those inputs are more informative than a promised monthly saving without workings.

Related guides for your next step

For supplier time windows and whole-house billing, see our heat pump tariff comparison.

To understand schedules and temperatures at handover, use our heat pump controls and settings guide.

If a system is already installed and performing poorly, use the heat pump problems guide for safe first checks and useful records.

For a side-by-side replacement decision, compare a heat pump with a gas boiler on installation, bills and everyday use.

Sources and method

The linked technical and supplier sources explain measurement, controls and tariff structures. All numerical scenarios are our own arithmetic using the assumptions shown. Installation spending is covered separately in our heat pump cost guide.

Images are AI-generated editorial illustrations.