Pool Heat Pump Size Calculator - What Size Do I Need In Australia?

Trying to size the heat pump for your swimming pool but not sure how big it should be? Use this pool heat pump size calculator to quickly work out the right size for your pool!

Note: Heat pump size calculations are very complex and the results depend upon on a number of assumptions. Take care when using this calculator and consider the results a rough estimate only.

Pool Heat Pump Size Calculator

Which months do you heat your pool?

What Size Heat Pump Do I Need For My Swimming Pool?

The size of heat pump necessary for your pool depends on a wide variety of factors, including:

  • Your climate (temperature, humidity, wind etc.)
  • Which months you plan on heating your pool
  • Pool surface area
  • Target temperature you will heat your pool to
  • Number of hours per day your heat pump will run
  • Whether you use a cover or not

As you can see, sizing your heat pump is a complex process that depends on a number of factors that are highly specific to YOUR pool. That's why I've made this calculator - so you can enter your pool details and get a result tailored to your circumstances.

However, as an example, we can calculate the size of a heat pump for a typical Australian swimming pool.

Take a typical swimming pool in Brisbane with a surface area of 36m², used to heat a pool from November through March to a temperature of 27°C, with a cover on the pool when it's not use.

If the owner would like to heat pump to run for only 10 hours per day, it will need to have an output of at least 12.6 kW. November will have the highest energy consumption and therefore dictates the size of the heat pump.

If the owner pays 28 cents per kilowatt-hour (c/kWh) for electricity, they can expect to pay around $3,700 for heating over this 5 month period.

Should You Oversize A Pool Heat Pump?

Yes. It's generally recommended that you oversize your pool heat pump, as this has a few benefits:

  • Capacity - ability to maintain desired temperatures even in unusually cold years
  • Flexibility - can run the heat pump for fewer hours per day if desired
  • Efficiency - larger units tend to have higher COP and therefore do more heating for the same electricity input
  • Faster - will heat up the water on start up faster than a smaller unit

Of course, oversizing your heat pump adds to the upfront cost, which is not desirable. In saying that, a larger unit with a higher COP (coefficient of performance) will actually save you money in the long run, so it might pay off in time.

How Do I Calculate What Size Heat Pump I Need?

To calculate the size of heat pump you need for your swimming pool, you'll need to enter the following information into this pool heat pump size calculator:

  • Pool surface area (in m²)
  • Nearest city (in Australia - for climate calculations)
  • Which months you heat your pool
  • Target water temperature when heating
  • Hours per day your heat pump will run
  • Whether you use a cover or not

Once you've entered this information, the calculator will tell you the required heat pump output (in kW) to meet your specifications.

Remember that this is the heat pump OUTPUT, not INPUT.

You can then tweak the information you entered into the calculator to see how each of these factors impact the required heat pump size.

Once you are happy, look up some heat pump spec sheets and see if you can find one that meets or exceeds your recommended heat pump output.

If you are sizing other pool equipment, check out this pump size calculator and filter size calculator.

Louis from Pool Advisor


A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.