The result is thermal output, not electrical input
Electricity use differs from the result. It depends on the unit’s efficiency and operating conditions.
Calculators
Water heating
Heat pump sizing calculator
Enter pool volume, temperature rise and desired warm-up time for an initial heating-capacity estimate.
Calculator
Initial heating-capacity estimate
Enter volume, target temperature and warm-up time. The allowance represents assumed heat losses and less favourable conditions; it does not replace manufacturer sizing.
Limitations
What this calculator cannot account for
Heat loss changes during the day
Wind, night-time temperature, surface area and cover use affect the output allowance required.
Check the required water flow
Even a correctly sized heat pump needs water flow within the manufacturer’s specified range.
Holding temperature differs from initial heating
Rapidly warming cold water can require more output than maintaining water that is already warm.
Related guides
Check volume, heat loss and operating conditions
FAQ
Frequently asked questions
Can I choose a specific model from this result?
No. It is only an initial thermal-output estimate. Model selection must account for climate, performance curves, water flow, air temperature and manufacturer recommendations.
Why add a heat-loss allowance?
The basic calculation heats only the water under ideal conditions. A real pool also loses heat at the surface and to its surroundings.
Does a cover reduce the capacity needed?
It reduces heat loss and can make temperature maintenance much easier. The exact benefit depends on the pool, weather and use.
What if the target temperature is below the current temperature?
The calculator shows zero heat required for a temperature rise. Cooling needs a different calculation.