Domestic hot water
Calculate thermal energy, electricity use and running cost to heat daily hot water by a chosen temperature rise.
Open calculatorAppliance electricity cost
Energy (kWh) = power in watts / 1,000 × hours per day × days. Multiplying by your electricity price per kWh gives the running cost.
Average power draw while running — note that fridges, washing machines and heat-pump dryers cycle rather than drawing peak nameplate watts continuously.
W
Daily operating hours — e.g. a kettle boiling for 6 minutes a day is 0.1 hours.
Number of days in the costing period (e.g. 30 for a month or 365 for a year).
Running cost
986 zł
Energy consumed
1,095 kWh
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A 2,000 W kettle that boils for 3 minutes uses 0.1 kWh (2,000 W × 3/60 h), not a full 2 kWh.
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Educational estimate only. Not medical, tax, legal or financial advice.