Heat pump cost calculator: what it costs to run, compared with your heating
Enter your federal state, floor area, energy class and current heating: the calculator shows what a heat pump would cost a year in electricity and how much you would save.
Worked through by Radif Partners · Editorial policy · How we calculate
Heat pump a year
€1,310
Gas boiler now: €2,403, difference €1,093
| Ground-source heat pump | €1,036 |
|---|---|
| Air-source heat pump | €1,310 |
| Oil boiler | €2,214 |
| Gas boiler (now) | €2,403 |
| Storage heaters | €4,620 |
| Heat demand a year | 16,229 kWh |
| CO₂ today a year | 3,765 kg |
Step-by-step calculation
- 140 m² × class E (midpoint 145.0 kWh/m²) × efficiency 86.6 % × North Rhine-Westphalia climate (2,929 degree days vs 3,236 in Potsdam, space heating only) = 16,229 kWh.
- Heat pump: 16,229 ÷ SPF 3.4 = 4,773 kWh × 27.44 ct = €1,310.
- Gas at 11.58 ct/kWh (Destatis, first half of 2026), heating oil at €118.68 per 100 litres.
- CO₂ price: €65 per tonne, as included in 2026 prices.
Estimate under the funding guideline and the law as of October 2026, not advice. Only the bank’s grant approval is binding. How we calculate
What a heat pump costs to run each year comes down to three numbers: the heat your house needs, the seasonal performance factor (SPF, Jahresarbeitszahl) and the electricity price. The calculator derives the heat from floor area, the energy class on the energy certificate and the degree days of your federal state, or from the gas or oil use on your last bill. For the SPF it uses the average the Fraunhofer ISE institute measured in existing German homes: 3.4 for air-to-water and 4.3 for ground source. The price is the heat pump tariff with a separate meter reported by the Federal Network Agency, 27.44 ct per kWh. A 140 m² house in class E in North Rhine-Westphalia needs about 16,229 kWh of heat. An air-source heat pump draws 4,773 kWh for it and costs €1,310 a year, against €2,403 for a gas boiler at the official average of 11.58 ct. That gap of €1,093 is what has to repay the purchase after the grant. A system as weak as the worst one measured (SPF 2.6) would cost €1,713.
How the heat pump calculator works
Step one is the heat your house needs in a year. Without a consumption figure, the calculator takes the midpoint of the energy class on your energy certificate (Energieausweis), converts it to useful heat with a boiler efficiency of 87 % and adjusts the space heating share to the climate of your state, using the degree days of the German weather service for 2021 to 2025. Hot water, about 19 % of the heat, stays the same everywhere. The class midpoint is an assumption; if you know your gas use, enter it and it replaces area and class.
The calculator then divides the heat by the SPF and multiplies the electricity by the tariff. The comparison boiler uses the gas price from the Destatis survey for the first half of 2026 and the heating oil price from the European Commission’s Weekly Oil Bulletin.
The SPF makes the difference
The Fraunhofer ISE field study in existing buildings shows how far units of the same type drift apart. For the North Rhine-Westphalia example house with 16,229 kWh of heat a year:
| SPF | Electricity a year | Cost a year |
|---|---|---|
| 2.6 (weakest air-to-water unit) | 6,242 kWh | €1,713 |
| 3.0 (minimum for the grant) | 5,410 kWh | €1,484 |
| 3.4 (air-to-water average) | 4,773 kWh | €1,310 |
| 4.3 (ground source average) | 3,774 kWh | €1,036 |
| 4.9 (best air-to-water unit) | 3,312 kWh | €909 |
Between the weakest and the best air-to-water system measured, the same house pays €804 a year more or less. The grant requires the system to be designed for an SPF of at least 3.0. The electricity your house needs is broken down under heat pump electricity use.
Which electricity price is used
The heat pump tariff comes from the Federal Network Agency monitoring report, as of 1 April 2025; no newer official figure exists. With its own meter the price was 27.44 ct per kWh, with one shared meter 31.70 ct. In the example house that is €1,310 against €1,513 a year. What a separate meter brings is worked out under heat pump tariff, the comparison with household power under heat pump electricity price.
Is a separate meter worth it?
Saving a year
€474
| Price gap | 11 ct/kWh |
| Worth it from | 0 kWh |
Enter fitting and standing charge of the second meter from your network operator’s quote.
What the calculator does not know
It knows neither your quote nor your grant. The running saving of €1,093 in the example only says something about value for money together with the purchase price. The grant is calculated under heat pump grant, the price after the grant under heat pump cost. The Destatis averages include the standing charge; servicing and the chimney sweep are in none of the figures.