How much does a heat pump cost to run per hour in NZ?

A 2.5 kW heat pump drawing around 660W of electricity costs roughly 25c per hour to run at the February 2026 national average retail rate of around 38c/kWh. Cold winter mornings derate the COP, pushing hourly cost closer to 35-40c.

Is a heat pump cheaper than a plug-in heater?

Yes - dramatically. A plug-in oil column heater converts 1 kWh of electricity into 1 kWh of heat. A heat pump with a COP of 3 produces 3 kWh of heat from the same 1 kWh of electricity. Running a 2,400W oil heater for 6 hours costs about $5.50; a heat pump producing the same heat costs $1.80.

Why do heat pumps advertise higher COPs than they deliver in winter?

Manufacturers rate COP at 7°C outdoor, which is a mild NZ autumn morning. On a 2°C Canterbury winter morning most split systems run at COP 2.5-2.8. Below 0°C it can drop to 2.0. The calculator uses a realistic winter COP for this reason.

How much does it cost to install a heat pump in NZ?

Installed cost in 2026 for a typical 2.5-3.5 kW split system is $2,500-$3,500 including labour. Larger ducted systems run $8,000-$14,000. Payback vs plug-in heating is usually under three years.

Field Note

How much does a heat pump cost to run in NZ?

Published 15 April 2026· 6 min read

A modern 2.5 kW heat pump running six hours a day costs about $45 a month in Christchurch at the February 2026 MBIE retail rate of 36.6 c/kWh. That's around $10 a week to heat a room properly through winter, roughly a third of what a plug-in oil column heater would cost to do the same job.

But the number depends on three things: the heat pump's , your local electricity rate, and how long you run it. Here's how to work out your own.

The formula

A "2.5 kW heat pump" means the unit delivers 2.5 kilowatts of heat into the room. The electricity it draws to do that is:

electricity drawn (kW) = heat output (kW) ÷ COP

is short for Coefficient of Performance, which is just a measure of how much heat you get out for each unit of electricity you put in. A good modern heat pump in Canterbury runs around COP 3.8 when it's 7°C outside. So:

2.5 kW of heat ÷ 3.8 = 0.66 kW of electricity drawn
6 hours a day × 0.66 kW = 3.95 kWh a day
3.95 kWh × 30.4 days × 36.6c/kWh = $44/month at the Feb 2026 Christchurch rate

In a colder winter month when COP drops to around 3.3, the same six hours costs closer to $50/month. Bear in mind the figure is a rate for a typical small household and may differ from your actual per-kWh rate, particularly if you are on a with a higher daily fixed charge.

COP depends on the weather

Heat pumps get less efficient the colder it gets - they have to work harder to pull warmth out of cold air. Typical COP ranges by region:

Auckland / Northland: COP 4.0-4.5 most of winter
Wellington / lower North Island: COP 3.7-4.0
Christchurch / Canterbury: COP 3.6-3.9 (cold mornings drop it)
Southland / Central Otago: COP 3.0-3.5 (frost country)

The COP printed on the unit sticker is usually the peak efficiency at a mild temperature. Real-world annual average COP is usually 0.3-0.5 lower.

Heat pump vs plug-in heater

The same 6 hours a day from a 2,400 W oil column heater: 2.4 kW × 6 h × 30.4 days × 36.6c = $160/month. That is $115 a month more than the heat pump for the same amount of heat in the room. Over a Canterbury winter (four months of heavy heating) that compounds to roughly $460 extra.

Work out your own number

The NZ Power Bill Calculator does this calculation live - tick the heat pump, set its heat output and COP, and it'll show you your monthly cost and the plug-in heater comparison for your region.

Related guides

What temperature to set your heat pump in NZ winter - how thermostat setting affects running cost
Insulation or a heat pump: where to spend first - why the building shell matters more than the heater
Heat pump vs wood burner: which is cheaper in NZ? - cost-per-kWh comparison