Pool Pump Electricity Cost
Calculate pool pump electricity cost from motor horsepower, efficiency, daily run time, and electricity rate.
Compare single-speed versus variable-speed savings.
Pool pumps are often the second or third largest electricity user in homes with pools. A single-speed 1.5 HP pump running 8 hours a day can cost $80-120 per month. This is where variable-speed pumps earn their premium.
Power calculation
kW = horsepower x 0.7457 / (motor_efficiency / 100)
kWh per day = kW x run_hours
Monthly cost = kWh per day x 30 x electricity_rate
A 1.5 HP motor at 80% efficiency draws: 1.5 x 0.7457 / 0.80 = 1.4 kW. At 8 hours per day and $0.13/kWh, that is $43.68 per month.
Variable-speed pumps
Variable-speed pumps (VSPs) use electronically commutated permanent magnet motors that are inherently more efficient and can run at low speed for filtration (using only 25-30% of the energy of a single-speed pump at full speed). They are mandated by California Title 20 for residential pools above 2 HP.
The energy savings from running at half-speed are dramatic because power scales with the cube of speed (affinity laws). At 50% speed, a pump uses only 12.5% of the power (0.5^3 = 0.125). In practice, VSPs running at low speed for 8 hours plus high speed for 1-2 hours still save 50-80% versus a single-speed pump running all day.
The upfront cost premium for a VSP ($800-1,500 versus $300-600 for single-speed) typically pays back in 1-3 years through energy savings.