Heat Pump Running Cost Calculator
Estimate what a heat pump costs to run each year and month in the UK, and compare it with a gas boiler at today's price cap.
Quick answer
A heat pump’s yearly running cost is the heat your home needs divided by the pump’s SCOP, multiplied by your electricity unit rate. A typical 3 bed semi needing 8,000 kWh of heat, with a SCOP of 3 at the Ofgem cap rate of 26.32p/kWh, costs about £702 a year, or £58.49 a month on average. The same heat from an 85% efficient gas boiler at 7.97p/kWh costs about £750.
How to use the heat pump running cost calculator
- Choose how you know your heat demand. Pick House size for a typical figure, Known kWh if you have a number from your EPC or heat loss survey, or Gas use to convert last year’s gas consumption into useful heat.
- Enter the house type or annual figure. The presets cover space heating and hot water for typical UK homes, from 4,500 kWh for a small flat to 15,500 kWh for a large detached house. For the gas option, enter the kWh on your annual statement.
- Enter the heat pump SCOP. This is the seasonal coefficient of performance: units of heat out for each unit of electricity in, averaged over a year.
- Check the electricity and gas rates and boiler efficiency. The defaults are the Ofgem price cap averages for October to December 2026 and an 85% condensing boiler. Replace them with your own tariff for a personal result.
- Read the result. The large number is the heat pump’s yearly electricity cost. The cards show the gas boiler cost for the same heat, the average monthly cost, the SCOP you need to match gas, and the heat delivered.
Heat pump running cost formula
The calculator finds the electricity needed to deliver your home’s heat, then prices it, and does the same for a gas boiler.
Where:
- Q is the useful heat your home needs in a year (kWh), for space heating and hot water. In Gas use mode, Q = gas kWh × η.
- SCOP is the heat pump’s seasonal coefficient of performance.
- Ehp is the electricity the heat pump uses in a year (kWh).
- Re and Rg are the electricity and gas unit rates in pence per kWh, divided by 100 to give pounds.
- η is the gas boiler’s real seasonal efficiency as a decimal, such as 0.85.
- Chp and Cgas are yearly running costs in pounds. The monthly figure is the yearly cost ÷ 12.
Worked examples
Example 1: 3 bed semi, SCOP 3
The home needs 8,000 kWh of heat a year. The heat pump has a SCOP of 3, and both fuels are on the October to December 2026 cap.
The heat pump uses 2,667 kWh of electricity and costs £58.49 a month on average, saving about £48 a year on unit costs.
Example 2: 4 bed detached, well designed system
A 4 bed detached house needs 11,500 kWh a year. A carefully designed system with low flow temperatures reaches a SCOP of 3.5.
The gas boiler would cost 11,500 ÷ 0.85 × 0.0797 = £1,078.29, so the heat pump saves about £213 a year on unit costs.
Example 3: from a gas bill, poorly performing pump
A household used 12,000 kWh of gas last year. At 85% boiler efficiency that delivered 10,200 kWh of heat. With a SCOP of only 2.5:
Last year’s gas cost 12,000 × 0.0797 = £956.40, so this heat pump would cost about £117 more. This is why SCOP matters so much.
Heat pump running costs by home size and SCOP
Yearly electricity cost at 26.32p/kWh, compared with an 85% gas boiler at 7.97p/kWh. Unit costs only, standing charges excluded.
| Heat demand | SCOP 2.5 | SCOP 2.8 | SCOP 3.0 | SCOP 3.5 | SCOP 4.0 | Gas boiler |
|---|---|---|---|---|---|---|
| 4,500 kWh (1 to 2 bed flat) | £473.76 | £423.00 | £394.80 | £338.40 | £296.10 | £421.94 |
| 6,500 kWh (2 to 3 bed terrace) | £684.32 | £611.00 | £570.27 | £488.80 | £427.70 | £609.47 |
| 8,000 kWh (3 bed semi) | £842.24 | £752.00 | £701.87 | £601.60 | £526.40 | £750.12 |
| 11,500 kWh (4 bed detached) | £1,210.72 | £1,081.00 | £1,008.93 | £864.80 | £756.70 | £1,078.29 |
| 15,500 kWh (5+ bed detached) | £1,631.84 | £1,457.00 | £1,359.87 | £1,165.60 | £1,019.90 | £1,453.35 |
At these cap rates the break-even SCOP is 26.32 × 0.85 ÷ 7.97 = 2.81. Above it, the heat pump is cheaper to run than the gas boiler.
What affects the result
SCOP and flow temperature
SCOP is the biggest lever. A heat pump works hardest when it must heat radiator water to a high temperature on a cold day. Systems designed for a flow temperature of 35 to 45 °C, with suitably sized radiators, reach much higher seasonal efficiency than those run at 55 °C or more. The Electrification of Heat trial found a median seasonal performance factor of 2.80 for air source heat pumps in British homes, with a wide spread between the best and worst installs, as reported by the Energy Systems Catapult.
Your unit rates
The defaults are 26.32p/kWh for electricity and 7.97p/kWh for gas, the averages for Direct Debit customers under the Ofgem price cap for 1 October to 31 December 2026. Electricity carries no VAT from October 2026 to March 2027, which helps heat pumps this winter. Many owners move to a heat pump or time-of-use tariff with cheaper overnight electricity, which can cut costs well below the cap figure. For a single appliance at any rate, the electricity cost calculator does the same pricing step.
Heat demand accuracy
The house presets are typical figures only. Insulation, glazing, draughts, room temperature and how many people use hot water change the real figure a lot. An MCS heat loss survey gives the best number. Converting your gas use is the next best option because it reflects how you actually heat your home. A full room-by-room estimate is possible with the heat loss calculator.
Boiler efficiency
Condensing boilers are rated around 90% or more, but in daily use many run hotter than they need to and achieve closer to 80 to 88%. A lower boiler efficiency makes the gas comparison more expensive and lowers the SCOP you need to break even.
Frequently asked questions
How much does a heat pump cost to run per month in the UK?
For a 3 bed semi needing 8,000 kWh of heat a year with a SCOP of 3, the average is about £58 a month at the October 2026 cap rate of 26.32p/kWh. Costs are not spread evenly: a winter month can be three or four times a summer month, when the pump mostly heats water.
Is a heat pump cheaper to run than a gas boiler?
It depends on the SCOP and the ratio of electricity to gas prices. With the October to December 2026 cap rates and an 85% boiler, a heat pump is cheaper once its SCOP is above about 2.81. A good installation with low flow temperatures and a time-of-use tariff can beat gas comfortably.
What SCOP should I use?
Use the design SCOP from your installer’s MCS quote if you have one. Otherwise 3 is a sensible starting point for a modern air source heat pump. UK field trial data found a median of 2.8, while well designed systems running at low flow temperatures often reach 3.5 to 4.
How do I find my home’s annual heat demand?
Check your EPC, which lists estimated space heating and hot water demand in kWh, or an MCS heat loss survey. If you heat with gas now, select Gas use and enter last year’s gas kWh. The calculator multiplies it by your boiler efficiency to get the heat your home actually used.
Does the result include standing charges?
No. It compares the unit cost of heat from each system. You keep paying the electricity standing charge either way. If you disconnect gas entirely, you also save the gas standing charge, which is 29.68p a day under the October 2026 cap, about £108 a year.