Home Heating Cost Calculator NZ

This calculator works out how much it actually costs to heat your home in New Zealand, and compares a heat pump against a plug-in electric heater so you can see why some heating options are so much cheaper to run than others. You enter the heat output you need in kilowatts, the hours you run the heater each day, the number of days in the heating season, your power price per kWh, and the coefficient of performance (COP) of your heat pump, typically around 3 to 4. From these figures the calculator returns the cost per hour of running the heat pump, the total season cost for both the heat pump and the electric heater, and the dollar saving from choosing the heat pump. The gap is large because a plug-in heater turns one unit of electricity into one unit of heat, while a heat pump moves several units of heat for every unit of power it uses. Use this tool to check whether your current heating is costing more than it should, to weigh up a new heat pump against sticking with existing heaters, or simply to understand your winter power bill. Real-world efficiency depends on the unit, its age and the outside temperature, and power prices vary between retailers, so treat the results as an estimate to guide your decision rather than an exact bill.

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$
$432
saved over the season by using a heat pump instead of a plug-in electric heater
Heat pump season cost$173
Electric heater season cost$605
Heat pump per hour$0.24

A heat pump coefficient of performance (COP) of around 3.5 means it delivers 3.5 units of heat per unit of electricity, while a plug-in heater has a COP of 1. Real efficiency varies with the unit and the outside temperature. Power prices change, so use your current rate. Estimate only, not financial advice.

How it works

The heat you need is the output in kilowatts times the hours used. A plug-in electric heater uses that much electricity directly. A heat pump uses far less, because it moves heat rather than generating it, dividing the electricity needed by its coefficient of performance. The calculator multiplies the electricity each uses by your power price and the days in the season to compare seasonal running costs, showing the saving from the more efficient option.

Worked example

Heating with 3 kW for 6 hours a day over 120 days at 28 cents a unit, a plug-in electric heater costs about $605 for the season. A heat pump with a COP of 3.5 delivers the same heat for about $173, a saving of roughly $432 over the season, which is why heat pumps are so much cheaper to run.

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Frequently asked questions

What is the cheapest way to heat a home in New Zealand?

A modern heat pump is usually the cheapest to run, because it moves several units of heat for each unit of electricity. A plug-in electric heater gives one unit of heat per unit of power, so it costs several times more for the same warmth.

Why is a heat pump cheaper than an electric heater?

A heat pump has a coefficient of performance, often around 3 to 4, meaning it delivers 3 to 4 units of heat per unit of electricity. A resistance heater has a coefficient of 1, so it uses far more power for the same heat.

How much does it cost to run a heater?

It depends on the heat output, the hours used, your power price and the efficiency of the heater. This calculator estimates the cost per hour and per season for the options you compare.