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Enter the litres of heating oil you use per year. The calculator turns them into the heat your house receives, then into the electricity a heat pump needs for the same heat, and compares the running costs.

Enter your values

Litres burned in a year, from your delivery notes.
Where do I find this?

Add up your deliveries for the year and correct for the tank level at the start and the end, or use the average of the last years.

About 10 kWh per litre of heating oil.
Where do I find this?

Heating oil contains about 10 kWh per litre as net calorific value, the basis on which boiler efficiencies are usually stated.

Share of the fuel energy that becomes heat. Often 75 to 90 % for oil boilers.
Where do I find this?

Old boilers are lower. The chimney sweep's flue-gas measurement only shows the combustion losses, so the yearly efficiency is a few points below that figure. 85 is an example.

Heat delivered per kWh of electricity over a year. Measured in existing houses: about 3.3 on average for air source, 3.6 to 5.2 for ground source.
Where do I find this?

The Jahresarbeitszahl (JAZ) is the yearly heat divided by the yearly electricity of the heat pump. Your installer gives an estimate for your house. 3.3, the average of air-source heat pumps in a Fraunhofer ISE field test in existing houses, is an example.

From your last delivery. Divide a price per 100 litres by 100.
Where do I find this?

The invoice shows the price per litre or per 100 litres. 1.00 is an example.

Per kWh. Heat pump tariffs are often cheaper than household tariffs.
Where do I find this?

Use the price per kWh from your contract or bill. 25 ct = 0.25.

Only changes the symbol; no exchange rate is applied.

Result

Enter your values to see the result.

Electricity for the heat pump
– kWh per year
Electricity per litre of oil replaced
– kWh
Heat your house gets
– kWh
Oil cost per year
–
Heat pump cost per year
–
Heat pump saves per year
– (negative = costs more)

Want this tracked for you? UtilityControl logs your meters and costs automatically.

How it is calculated

  • Heat delivered = litres × energy per litre × boiler efficiency ÷ 100
  • Heat pump electricity = heat delivered ÷ seasonal performance factor
  • Costs: oil = litres × price per litre; heat pump = electricity × price per kWh; saving = oil − heat pump

Example

2,000 litres × 10 kWh × 85 % = 17,000 kWh of heat. A heat pump with a factor of 3.3 needs 17,000 ÷ 3.3 = 5,152 kWh of electricity, about 2.6 kWh per litre of oil. At 0.25 per kWh that is 1,288, against 2,000 for the oil, a saving of 712 a year.

What this estimate leaves out

A new heat pump may heat a better insulated house, so the real heat demand can fall. Investment, grants, maintenance, price changes and the real performance factor are not included.

Sources: Fraunhofer ISE: heat pump field test in existing buildings, 2024 (in German) · Bundesverband Geothermie: net and gross calorific values of fuels (in German)

Written and reviewed by QLines, Cologne · Last reviewed

Guide: running a heat pump is not like an oil boiler · Replacing an oil boiler in Bavaria? Energy advice from SigmaEnergie (in German)

FAQ

Frequently Asked Questions

How much electricity does a heat pump need to replace heating oil?

Convert the oil to delivered heat (litres × 10 kWh × boiler efficiency), then divide by the heat pump's seasonal performance factor. 2,000 litres at 85 % efficiency need about 5,200 kWh of electricity with a factor of 3.3.

How many kWh of electricity replace one litre of heating oil?

A litre gives about 10 kWh of fuel energy, around 8.5 kWh of heat at 85 % boiler efficiency. A heat pump with a factor of 3.3 needs about 2.6 kWh of electricity for that heat.

Is a heat pump cheaper than an oil boiler?

Often yes: the heat pump needs only about a quarter to a third of the energy, as electricity. Compare the electricity price per kWh and the oil price per litre in the calculator.

What factor should I use?

Ask your installer for the expected seasonal performance factor (Jahresarbeitszahl) for your house. In a Fraunhofer ISE field test in existing houses, air-source heat pumps averaged 3.3 (2.4 to 4.0) and ground-source heat pumps reached 3.6 to 5.2.

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