Hot water heating cost calculator
Heating water for four people costs about 1,214 PLN a year with a central heat pump, about 1,333 PLN with a gas boiler and about 4,248 PLN with an electric water heater on the G11 tariff (example with a 200 l tank). Enter your household, water use and the prices from your bill to see the yearly cost and the price of one shower.
Example: 4 people, 47 l per person a day
Cheapest: Central heat pump, about 1,214 PLN a year
about 101 PLN a monthheat about 4,085 kWh/yrincl. tank about 491 kWh
- Central heat pump: about 1,214 PLN a year
- Gas boiler: about 1,333 PLN a year
- Hot water heat pump: about 1,699 PLN a year
- Pellet boiler: about 2,285 PLN a year
- Electric water heater, G12: about 3,023 PLN a year
- Electric water heater, G11: about 4,248 PLN a year
Difference between the cheapest and the most expensive source: about 3,034 PLN a year.
Bar scale: up to 5,000 PLN/yrPrices from 11 October 2026, estimate
| Heat source | Yearly purchase | Yearly | Shower | Bath |
|---|---|---|---|---|
| Central heat pump | 1,167 kWh | 1,214 PLN | 0.66 PLN | 1.56 PLN |
| Gas boiler | 4,300 kWh | 1,333 PLN | 0.73 PLN | 1.71 PLN |
| Hot water heat pump | 1,634 kWh | 1,699 PLN | 0.93 PLN | 2.18 PLN |
| Pellet boiler | 981 kg | 2,285 PLN | 1.25 PLN | 2.93 PLN |
| Electric water heater, G12 | 4,085 kWh | 3,023 PLN | 1.65 PLN | 3.88 PLN |
| Electric water heater, G11 | 4,085 kWh | 4,248 PLN | 2.32 PLN | 5.45 PLN |
Assumptions and formulaPrices from 11 October 2026
Heat in the water at the tap, your inputs
4 people × 47 l × 365 days × 4.19 kJ/(kg·K) × (55 − 10) K ÷ 3600 = 3,594 kWh/yr
Standing losses of the tank
200 l × 0.28 W/l × 8,760 h ÷ 1000 = 491 kWh/yr
Q = 3,594 + 491 = 4,085 kWh/yr
Yearly cost of each source
cost = Q ÷ efficiency × price
- Electric water heater, G11÷ 1.00 × 1.04 PLN/kWh
- Electric water heater, G12÷ 1.00 × 0.74 PLN/kWh
- Gas boiler÷ 0.95 × 0.31 PLN/kWh
- Hot water heat pump÷ 2.50 × 1.04 PLN/kWh
- Central heat pump÷ 3.50 × 1.04 PLN/kWh
- Pellet boiler÷ (4.9 kWh/kg × 0.85) × 2,330 PLN/t
One wash, water mixed to 40°C
64 l × 4.19 × (40 − 10) ÷ 3600 = 2.23 kWh
- Specific heat of water (1 l = 1 kg)
- 4.19 kJ/(kg·K)Energy performance certificate methodology, Polish Journal of Laws 2015 item 376
- Losses of a 200 l tank in a heated room
- 0.28 W/l with 100 mm, 0.40 W/l with 50 mmEnergy performance certificate methodology, Polish Journal of Laws 2015 item 376
- Electric heater: efficiency
- 100 %
- Gas boiler: efficiency
- 95 %
- Pellets: 4.9 kWh/kg, boiler efficiency
- 85 %
- Hot water heat pump: yearly COP
- 2.5Example: yearly COP 2.5-3; Hewalex PCWU 200eK has COP 3.67 in test conditions
- Central heat pump: SCOP
- 3.5
- Electricity price, G11
- 1.04 PLN/kWhURE G11 tariffs 2026 (PGE, Tauron, Enea, Energa), average with distribution
- Average electricity price, G12
- 0.74 PLN/kWhPGE 2026 tariff, G12, energy with variable charges, gross
- Gas price
- 0.31 PLN/kWhmyORLEN (formerly PGNiG OD) W-3.6 tariff, Oct 2026, with PSG distribution
- Pellet price
- 2,330 PLN/tMedian price of bagged pellets from producers and depots, Murator, Oct 2026
- G12: cheaper zone share in the example
- 80 %Example from our guide: the water heater runs mostly at night
- Shower, example
- 64 l at 40°C (8 min × 8 l/min)
- Bath, example
- 150 l at 40°C
An estimate. Fixed charges, pipe and circulation losses, cold water and sewage and the device itself are not included.
How electricity, gas, pellet and coal prices have changed, month by month. Price history
Ready-made calculations
How to use the calculator
- Enter the number of people and how much hot water one person uses a day. If you have no reading, keep 47 l.
- Check the cold water temperature and the tank setting. The defaults are 10°C and 55°C.
- Pick a tank or instant heating and switch on the heat sources you want to compare.
- Enter the prices from your bill and the heat pump COP, or keep the defaults. Click Calculate cost.
How we work out the cost
The heat in the water comes from its specific heat: litres × 4.19 kJ/(kg·K) × temperature rise ÷ 3600. Four people using 47 l a day each draw 68,620 l of 55°C water a year. Heating it from 10°C takes about 3,594 kWh.
Then come the tank losses. A 200 l tank with 100 mm of insulation in a heated room loses 56 W around the clock, about 491 kWh a year. In total the heat source has to deliver about 4,085 kWh. The cost is that heat divided by the efficiency of the device and multiplied by the energy price.
47 litres per person is about 898 kWh of heat a year, almost the same as the 900 kWh that the heating cost calculator adds to a house. That calculator leaves out tank losses.
What hot water costs for four people
With the default prices, a heat pump that also heats the house (SCOP 3.5) is the cheapest at about 1,214 PLN a year. A gas boiler costs about 1,333 PLN, a hot water heat pump with COP 2.5 about 1,699 PLN and a pellet boiler about 2,285 PLN.
An electric water heater costs about 3,023 PLN on the G12 tariff and about 4,248 PLN on G11, about 3.5 times as much as the heat pump. A hot water heat pump instead of an electric heater on G11 saves about 2,549 PLN a year.
What one shower and one bath cost
A shower is e.g. 8 minutes at 8 litres a minute, so 64 l of water at 40°C. Heating it from 10°C takes about 2.23 kWh: about 2.32 PLN with an electric heater on G11, 1.65 PLN on G12, 0.73 PLN with a gas boiler and 0.66 PLN with a central heat pump.
A bath is e.g. 150 l of water at 40°C and about 5.24 kWh of heat: about 5.45 PLN with an electric heater on G11, 1.71 PLN with gas and 1.56 PLN with a heat pump. The cost of one wash leaves out tank losses, because the tank loses heat whether anyone bathes or not. Cold water and sewage are billed separately by the water company.
What the calculator leaves out
The result does not include fixed charges, buying and servicing the devices, or pipe and circulation losses. The Polish energy certificate methodology assumes that 60-80% of the heat prepared for hot water reaches the taps in a single-family house, so a long installation with circulation will cost more.
The central heat pump uses SCOP 3.5, as for space heating. When it heats water to 55°C its COP is usually lower, so enter the value from the data sheet if you know it. The G12 tariff changes the price for the whole meter, including cooking and lighting.
Frequently asked questions
How much does it cost to heat water with an electric water heater?
For four people about 4,248 PLN a year on the G11 tariff at 1.04 PLN/kWh. On G12, if the heater takes e.g. 80% of its power in the cheaper zone (PGE rates), about 3,023 PLN. Both include about 491 kWh of losses from a 200 l tank.
Hot water heat pump or electric water heater: which is cheaper to run?
A hot water heat pump with COP 2.5 costs about 1,699 PLN a year for four people, an electric heater on G11 about 4,248 PLN. The difference is about 2,549 PLN a year, before the purchase price and servicing.
How much does one shower cost?
A shower of e.g. 64 l at 40°C needs about 2.23 kWh of heat. That is about 2.32 PLN with an electric heater on G11, 0.73 PLN with a gas boiler and 0.66 PLN with a central heat pump.
How much does a bath cost?
A bath of e.g. 150 l at 40°C takes about 5.24 kWh of heat: about 5.45 PLN with an electric heater on G11, 1.71 PLN with gas and 1.56 PLN with a central heat pump.
How many kWh does it take to heat 1 m³ of water?
About 52.4 kWh to heat it from 10 to 55°C. With the default prices that costs about 54.47 PLN with an electric heater on G11, 17.09 PLN with gas and 15.56 PLN with a central heat pump.