Skip to content
exactfigure.com
Changes the currency unit, not the numeric value. No conversion is performed.

Heat Pump Cost Calculator

Use the Heat Pump Cost Calculator to compare your current gas or oil heating system with a heat pump. Based on your annual fuel use, SPF and electricity price, it estimates the heat pump’s electricity demand and annual running costs. It also shows the SPF or electricity price at which the two systems reach the same running cost. Investment costs and payback can be included optionally.

All defaults are example assumptions. This is a static scenario based on your own figures — not a suitability check, not sizing, not a subsidy calculation, not a recommendation, and no market or live prices. The calculation runs in your browser; nothing is stored.

1. Your current heating
What do you heat with today?

Shows how much of the fuel energy supplied over the year becomes useful heat. This is different from the heat pump’s SPF.

2. Heat pump

SPF/JAZ = annual heat delivered divided by annual electricity used (your assumption, not a momentary COP).

Investment & payback (optional)Extra investment, grant and comparison period

What your result means

If the operating break-even SPF is below your assumed SPF, the heat-pump running cost is lower than the old one in this scenario; if it is above, it is higher. The maximum electricity price tells you up to which price per kWh the heat pump, at your SPF, does not exceed the old total cost. Every figure holds only under your inputs and is not a promise.

How this calculator works

First the fuel energy is set: for gas this is simply your yearly figure in kWh; for heating oil it is litres times the energy content per litre (a starting value of about 10 kWh/l — an editable approximation, not an exact universal constant). Fuel energy times the old system's annual utilisation efficiency gives the useful heat. The annual utilisation efficiency describes the old heating system — the ratio of useful heat produced over the year to the final energy supplied — and is a different thing from the heat pump's SPF.

The heat pump is described by its SPF, treated here purely as annual heat delivered divided by annual electricity consumed. So the electricity demand is useful heat divided by the SPF. The old running cost is the variable energy cost (use times price) plus the old fixed cost; the heat-pump running cost is electricity demand times the electricity price plus the heat-pump fixed cost. The difference is the annual saving, which can also be negative.

The operating break-even is the SPF at which the heat-pump running cost equals the old total cost. The maximum electricity price is the price at which the two are level at your SPF. Where such a break-even is not mathematically meaningful (for example when the heat-pump fixed cost alone already reaches the old total cost), it is shown as a plain-text state, never as an infinite value.

Optionally the calculator compares the extra investment against a replacement you would need anyway: extra investment = net heat-pump cost (investment minus grant) minus that replacement. This extra investment may be negative — then the heat pump is already cheaper to buy, net, than the replacement, and there is no additional investment left to pay back. A positive extra investment together with a positive annual saving gives the static payback; the investment break-even is the SPF at which the extra investment is just recovered over your comparison horizon. Over the horizon H the calculator also sets the two paths' static totals side by side: old path = replacement alternative + H × old total cost, heat-pump path = net heat-pump investment + H × heat-pump total cost. All investment figures are static and nominal: no present value/discounting (no NPV), no future energy-price growth, no financing. No subsidy rules are calculated — the grant is only an amount you enter.

Formula and variables

Fuel energy = gas use, or oil litres × energy content per litreUseful heat = fuel energy × annual utilisation efficiencyHeat-pump electricity = useful heat / SPFOld total cost = use × price + old fixed costHeat-pump total cost = electricity × price + heat-pump fixed costAnnual saving = old total cost − heat-pump total costOperating break-even SPF = useful heat × electricity price / (old total cost − heat-pump fixed cost)Max. electricity price = (old total cost − heat-pump fixed cost) × SPF / useful heatNet heat-pump investment = heat-pump investment − grantExtra investment = net heat-pump investment − replacement alternativeStatic payback = extra investment / annual savingInvestment break-even SPF = useful heat × electricity price / (old total cost − heat-pump fixed cost − extra investment / horizon)Old path over H years = replacement alternative + H × old total costHeat-pump path over H years = net heat-pump investment + H × heat-pump total cost
Annual utilisation efficiency
estimated yearly efficiency of the OLD heating system, in percent — the share of the fuel/final energy supplied that becomes useful heat over the year (fuel energy × annual utilisation efficiency = useful heat); not the heat pump's SPF
SPF/JAZ
the heat pump's seasonal performance factor: annual heat delivered divided by annual electricity used (your assumption)
Energy content per litre
heating-oil approximation, starting value about 10 kWh/l, editable — not an exact universal value
Price
your entered gas/electricity price in ct per kWh, or oil price in EUR per litre (no market or live prices)
Fixed cost
annual fixed cost of each system in EUR (e.g. standing/metering charges; 0 is allowed)
Horizon
comparison period in years for the optional investment calculation

Worked examples

Example 1: a gas system using 18,000 kWh a year

Example inputs
FuelGas
Annual gas use18,000 kWh
Old annual utilisation efficiency85%
Gas price10 ct/kWh
Old fixed cost€240.00
Heat-pump SPF3.5
Electricity price30 ct/kWh
Heat-pump fixed cost€120.00
Example results
Useful heat per year15,300 kWh
Heat-pump electricity per year4,371.43 kWh
Old running cost per year€2,040.00
Heat-pump running cost per year€1,431.43
Annual saving€608.57
Operating break-even SPF2.39
Max. electricity price at SPF 3.543.92 ct/kWh

Useful heat = 18,000 × 85% = 15,300 kWh, electricity = 15,300 / 3.5 ≈ 4,371.43 kWh. Old total = 18,000 × €0.10 + €240.00 = €2,040.00, heat-pump total = 4,371.43 × €0.30 + €120.00 ≈ €1,431.43, about €608.57 less per year. The operating break-even is an SPF of 2.39; up to 43.92 ct/kWh the heat pump at SPF 3.5 is not dearer than the old system. All figures are example assumptions.

Example 2: an oil system using 2,000 litres a year, with the optional investment

Example inputs
FuelHeating oil
Annual use2,000 l
Energy content (approx.)10 kWh/l
Old annual utilisation efficiency80%
Oil price€1.00/litre
Old fixed cost€300.00
Heat-pump SPF4.0
Electricity price28 ct/kWh
Heat-pump fixed cost€150.00
Investment / grant / replacement25,000 / 7,000 / 8,000 €
Horizon20 years
Example results
Heat-pump electricity per year4,000 kWh
Old running cost per year€2,300.00
Heat-pump running cost per year€1,270.00
Annual saving€1,030.00
Operating break-even SPF2.08
Extra investment€10,000.00
Static payback9.7 years

Fuel energy = 2,000 × 10 = 20,000 kWh, useful heat = 20,000 × 80% = 16,000 kWh, electricity = 16,000 / 4 = 4,000 kWh. Old total = 2,000 l × €1.00/l + €300.00 = €2,300.00, heat-pump total = 4,000 × €0.28 + €150.00 = €1,270.00, so €1,030.00 less a year. Net investment = 25,000 − 7,000 = €18,000, extra investment over the replacement = 18,000 − 8,000 = €10,000.00; statically that pays back in about 9.7 years. Purely nominal, with no discounting and no price growth. All figures are example assumptions.

Assumptions

  • Prices, SPF and efficiency stay constant within the scenario (your assumptions — real values vary; example assumption).
  • The annual utilisation efficiency captures the old system's losses; the SPF captures the heat pump's annual performance — two separate values you set yourself.
  • The heating-oil energy content (starting value about 10 kWh/l) is an editable approximation, not an exact universal value.
  • The investment calculation is static and nominal: no present value/discounting (no NPV), no energy-price growth, no financing.

Limitations of this calculator

  • No suitability check: no heat load, no kW sizing, and no statement on whether the building, radiators or flow temperature are a fit.
  • No subsidy rules, no eligibility, no future energy prices, no legislation, and no CO₂, PV, financing or tax effects.
  • No product or manufacturer recommendation and no personal recommendation to switch or not to switch — the figures are scenarios under your assumptions.
  • All values are approximations based on your inputs; the calculator makes no savings promise.

Frequently asked questions

How much electricity does a heat pump need instead of my gas or oil heating?

The calculator converts your use into useful heat via the annual utilisation efficiency, then divides that by the SPF you assume. The result is the estimated yearly electricity demand under your assumptions — not a measured or guaranteed figure for your specific building.

What is the difference between annual utilisation efficiency and SPF?

The annual utilisation efficiency describes the old heating system: how much useful heat over the year comes from the final energy supplied. The SPF describes the heat pump: annual heat delivered divided by annual electricity used. They are separate values and are entered separately here.

At which SPF does the heat pump become cheaper?

That is the operating break-even SPF: if your assumed SPF is above it, the heat-pump running cost is lower than the old total cost in this scenario; below it, higher. The value holds only for the prices and quantities you entered.

Does the tool use current prices or subsidies?

No. All prices, the SPF, the efficiency and any grant amount are your own inputs. The calculator uses no market, daily or live prices and calculates no subsidy rules or eligibility.

Does the calculator tell me whether switching is worth it for me?

No. It gives scenario figures for electricity demand, running cost and break-even under your assumptions. Whether a switch is technically possible and sensible depends on heat load, building, radiators and much more, and is not part of this calculation.

Sources and further reading

Official and independent sources on this topic. The links open each website in a new tab; no content is loaded from them into this page.

  • Kosten und Förderung: Womit muss ich bei einer Wärmepumpe rechnen?VerbraucherzentraleNeutral German consumer guidance on estimating heat-pump electricity from consumption and the seasonal performance factor, and on possible extra fixed/metering costs. No live prices, no product recommendation.
  • Jahresnutzungsgrad (glossary)UmweltbundesamtDefinition of annual utilisation efficiency as the ratio of annual useful heat to final energy supplied — the basis for the old-system useful-heat input.

Spotted an error in the calculation or the text?

If you notice something that is wrong or unclear: let us know via the contact page. We review every report.

Last reviewed: 04/10/2026 · All calculations run in your browser – inputs are not stored. ·How we check our calculators