It's simple math: watts × hours × rate.

Take your pump’s wattage, multiply by hours run, multiply by your electricity rate.

Find the wattage on the pump’s nameplate or in the manual. A typical 1.5 HP pump pulls around 1500 watts. Divide by 1000 to get kilowatts (1.5 kW). Multiply by how many hours you run it. Multiply by your local rate per kWh (check your electric bill).

Example: 1.5 kW × 1 hour × $0.12/kWh = $0.18 per hour. Run it 8 hours a day? That’s $1.44.

This assumes full speed. If you have a variable speed pump and run it low, the wattage drops dramatically. A variable pump at low speed might use 300 watts, so about $0.036 per hour. Worth knowing before you install a timer or decide to upgrade.