Watt Usage In Heat Pumps – A Simple Explanation

Josh Mitchell

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Josh Mitchell

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Holly Curell

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Understanding heat pump wattage is the key to knowing your electricity costs, and it can help homeowners stay on top of ever-rising bills.

In this guide, I'll show you exactly how to work out your heat pump wattage and running costs and explain how you can improve your heat pump efficiency to lower your monthly electric bill.

Why Wattage Of Heat Pump Matters?

Heat Pumps offer an effective way to control your home environment by regulating the temperature. However, alongside the cost of buying and installing a heat pump, you need to know how much it will cost to run.

There are 2 main reasons why you should have a good idea of your heat pump wattage:

1. It Explains Running Costs

The wattage directly influences the operating costs of your heat pump system. Knowing the wattage lets you estimate your electricity expenses and helps you make informed decisions about its affordability. It can also help you use the unit more efficiently. 

2. It's Used For Sizing Breaker And Wires

Knowing the wattage is essential for electrical compatibility, letting you check whether the heat pump will work with your building's electrical infrastructure. If it's not sized appropriately for the circuit breaker, you may trip or overload the circuits.

How Many Watts Does A Heat Pump Use?

Heat pumps convert electrical power (wattage) into heating or cooling power. Heat pump wattage varies depending on the size, efficiency, make, model, and technology used in the unit. 

The wattage of your heat pump correlates with the tonnage and BTU output. Higher tonnage/BTU output indicates more cooling or heating capacity, and your heat pump will have a higher wattage requirement to heat or cool the space. 

The average residential heat pump uses 3,000 - 7,000 watts (3-7 Kilowatts). Commercial heat pumps can use over 25,000 watts (25 Kilowatts) because they have a larger size and increased capacity. 

The table below shows the average wattage and running costs for different capacity heat pumps. I have used an average of 13.4 cents per kWh for these examples. 

Heat Pumps
Per Ton


Wattage (kW)

Cost of Electricity
(dollars per hour)

2 Ton




2.5 Ton




3 Ton




4 Ton




5 Ton




How To Determine Heat Pump Wattage And Running Cost

The above table will give you a rough indication of your heat pump's wattage, but here are a few ways to find the exact figure:

Determining Through Specsheet

The easiest way to find the heat pump wattage is on the specsheet/user information. Most manufacturers list the wattage in the heat pump manual, and some even provide rough running costs.

If you don't have a specsheet I recommend checking the manufacturer's website or contacting customer support.

Calculating Using BTU And COP

If you don't have the wattage, you can work it out using the BTU and the Coefficient of Performance (COP):

  • BTU = the heating or cooling output.
  • COP = the ratio of heating/cooling output to electrical input, showing the heat pump efficiency. The COP will be higher for Mini-Split and Geothermal heat pumps because they operate more efficiently.

You should be able to find both figures in the product manual. 

To work out the wattage, use this equation:

BTUs / COP = Wattage

For example, if your heat pump produces 24,000 BTU and has a COP of 3, the wattage would be:

24,000 / 3 = 8,000 Watts

Running Costs

To determine the running costs, you need 3 pieces of information:

1. Wattage in Kilowatts (determined using one of the methods above)

2. The number of hours it runs daily

3. The electricity cost per kWh - found on your electricity bill statement. The average kWh in the USA in 2023 is $0.16, but it varies in different regions. 

Once you have those figures, use this equation to calculate the daily running costs:

Kilowatts x hours run x cost per kWh = daily cost

If you only want the cost per hour, use the equation Kilowatts x cost per kWh

You can multiply the daily cost by 7 to find the weekly cost, multiply the weekly cost by 4 to find the monthly running cost, and multiply the monthly cost by 12 to find the yearly running cost. 

Here's an example of a 5,000-watt (5-kilowatt) heat pump that runs 6 hours a day with an electricity cost of $0.16 per kWh. 

5 x 6 x 0.16 = $4.80 per day to run

That translates to:

$33.60 a week

$134.40 a month

$1612.80 a year

Factors That Effect Power Consumption

As you can see, a heat pump can be an expensive home appliance. Understanding how different factors can help you become more efficient, potentially saving you hundreds of dollars a year, and should impact which you choose to buy

There are 5 main factors to consider:

1. Heat Pump Type

There are three main types of heat pumps: air-to-air, water source, and geothermal. They each operate and consume power differently:

  • Geothermal heat pumps work by drawing heat from the ground into your home. These are the most efficient (often with COP ratings over 4) and use very little energy, but are more expensive to install.
  • Water-source heat pumps operate similarly but draw energy from water under the ground rather than the earth. They are slightly less efficient but still have very low energy consumption.
  • Air-to-air heat pumps are the most common and work by transferring heat through the air into your home. They are less efficient (typically with a COP rating of 2.5-4) but are cheaper to install.

Ductless mini-split heat pumps use air-to-air heat transfer across multiple zones. I recommend them as a cheaper alternative to central HVAC systems for heating/cooling larger homes.

2. Getting the Right BTU Size for Your Space

The output of your heat pump is measured in BTUs (or tons) and shows how much heating/cooling it can provide. The higher the BTUs produced, the more watts it will need and the higher your electricity costs. 

Typically, larger spaces need higher BTU outputs. Oversized heat pumps can waste energy, while undersized heat pumps can lead to increased running times, increasing electricity costs.

Sizing your heat pump appropriately will maximize efficiency and lower energy costs. The area it can cover should be shown in the specifications. 

3. General Maintenance of the Unit

Regular maintenance of your heat pump will reduce wear and tear, improve performance, and identify potential issues early. A well-maintained system will operate efficiently and lower your running costs. I recommend checking the heat pump once a month, and having it professionally serviced at least once a year.

4. Insulation Quality of Your Space

Good insulation will minimize heat loss and heat gain, reducing the workload of your heat pump. This will improve performance and efficiency, and lower your running costs. At a minimum, I recommend:

  • Sealing air leaks around windows and doors
  • Adding wall and floorboard insulation, especially in garages or attics

5. Overall Climate and Ambient Temperature

More extreme or changing climates will require your heat pump to work more, increasing energy costs. If you live in an area with cold winters and hot summers, you should expect to pay more for electricity - but insulation can make a big difference!

How To Save Money When Using A Heat Pump

Heat pumps can be expensive, but there are some tips to keep the overall cost down:

  • Get The Right Size
  • Clean And Maintain The Heat Pump
  • Adapt The Settings
  • Turn It Off
  • Insulate Your Home


How Many Watts Do Heat Pumps Use With Heat Strips?

Heat pumps with heat strips offer an auxiliary heating component for cold temperatures but require significantly more wattage. Depending on the make/model of your heat pump, it could double the electricity consumption.

What Size Generator Do I Need to Run a Heat Pump?

Your generator will need a higher wattage than the combined wattage of all the appliances connected to it. I recommend a generator with a slightly larger capacity than your heat pump, e.g. If your heat pump is 7,000 Watts, you need a heat pump with at least 8,000 Watts.

Do Heat Pumps Stop Working When It's Very Cold Outside?

Most heat pumps will stop working around 14°F, but some can go as low as -4°F before they stop working. However, the heat pump efficiency will decrease as temperatures drop, providing less effective heating and cooling.

Does a heat pump use a lot of electricity?

Heat pumps are more energy-efficient than most other heating/cooling systems, but the electrical consumption will vary depending on the size and efficiency of the model and the climate it's operating in.

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Josh Mitchell


Josh Mitchell
My name is Josh and I am obsessed with home appliances. From portable AC units to heaters and air purifiers, I enjoy testing, learning and using these devices to improve the air quality inside my family home.

My Favorite Home Appliance?

Midea U Shaped Window Air Conditioner

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