Pool Heating Cost Calculator

About this calculator

Heating a pool by a given temperature rise takes a fixed amount of energy determined by physics — energy = pool volume × water's specific heat × temperature rise — and the calculator then divides that by your heater's efficiency, since gas heaters typically run at 80–95% efficiency, electric resistance heaters near 100%, and heat pumps deliver a coefficient of performance of roughly 4–6 (meaning they move 4–6 units of heat per unit of electricity consumed). The result in kWh or therms is then multiplied by your local energy price to get the cost.

Pool owners run this calculation when comparing heater types before purchase, since a heat pump's much higher COP can make it dramatically cheaper to run than a gas heater or electric resistance heater despite a higher upfront cost, or when deciding whether it's worth heating the pool at all for a short swim season. It also helps set realistic expectations for how long a given heater will take to reach the desired temperature.

This calculator takes your pool volume, desired temperature rise, heater efficiency and energy price, and returns the energy needed and what it will cost.