Estimate your well pump's monthly and yearly energy use and pump-only electricity cost from running watts, run time, and your electric rate.
Table of contents
How to use our Well Pump Electricity Cost Calculator
- Choose "Hours per day" if you know total daily pump run time, or choose the cycle method if you observed normal pump cycles.
- Enter Pump running power (watts) from a running-power label, paperwork, or measurement. Do not use motor horsepower or starting surge watts.
- Enter either Pump run time (hours per day), or both Pump run time per cycle (minutes) and Pump cycles per day.
- Enter Electricity usage rate (cents per kWh) from your bill. Include charges that change with kWh, but leave out fixed monthly charges.
- Calculate, then check Estimated pump run time per day. If it seems too high for your household, recheck the observed cycle length and count before relying on the cost estimate.
Definitions
Running electrical power: The power the pump uses while operating, measured in watts (W). This calculator uses this value, not motor horsepower or starting surge power.
kWh: Kilowatt-hour, a unit of electrical energy. A 1,000-watt pump running for one hour uses 1 kWh.
Cycle: One period from pump start until the pump stops. Cycle length is entered in minutes.
Usage rate: The electricity price that changes when you use another kWh, entered in cents per kWh. It can include supply, delivery, riders, and usage-based taxes.
Incremental energy cost: The extra electricity charge caused by pump operation. It does not include fixed customer, meter, or connection charges.
Common mistakes and quick fixes
Mistake: Entering motor horsepower in Pump running power (watts).
Fix: Enter running electrical watts from the motor or control box, paperwork, or a power measurement.
Mistake: Using starting surge watts for Pump running power (watts).
Fix: Use continuous running watts. Surge power is brief and does not describe normal kWh use.
Mistake: Entering water-available time instead of Pump run time (hours per day).
Fix: Enter only the total time the pump motor is actually running.
Mistake: Mixing units by entering hours in Pump run time per cycle (minutes).
Fix: Enter the length of one normal running cycle in minutes, then enter Pump cycles per day separately.
Mistake: Adding a fixed customer or meter charge to Electricity usage rate (cents per kWh).
Fix: Use only supply, delivery, rider, tax, and other charges that change with kWh.
Mistake: Treating Estimated pump electricity cost per year as the full utility bill.
Fix: It is the pump-only incremental energy cost and excludes fixed utility charges and other household electricity use.
Limitations & Key Assumptions / Boundary Conditions
- The estimate assumes Pump running power (watts) stays the same whenever the pump runs. Actual draw can differ from a nameplate value.
- Monthly energy use is defined as 30 days, and yearly energy use is defined as 365 days.
- Estimated pump electricity cost per year assumes the entered daily run time continues all year. Irrigation, visitors, leaks, and seasonal occupancy can change actual pumping.
- The calculation covers pump electricity only. It does not include fixed utility charges, other water-system equipment, repairs, or water use.
- Cycle observations can vary from day to day. Use an average cycle length and a cycle count that reflects a normal day.
- A cycle-based run time cannot exceed 24 hours per day. Values above that indicate incompatible cycle inputs.
Methodology
Calculation method
The calculator first finds daily pump run time. It uses the direct entry in hours mode, or converts cycle observations from minutes to hours in cycle mode.
daily_runtime_hours = direct_hours
daily_runtime_hours = (cycle_minutes * cycles_per_day) / 60
It converts watts to kilowatts, then multiplies by daily run time to find daily energy use.
daily_energy_kwh = (pump_power_watts / 1000) * daily_runtime_hours
Monthly and yearly energy use use planning periods of 30 and 365 days. The usage rate is converted from cents to dollars before calculating cost.
monthly_energy_kwh = daily_energy_kwh * 30
annual_energy_kwh = daily_energy_kwh * 365
monthly_energy_cost = monthly_energy_kwh * (electricity_rate_cents / 100)
annual_energy_cost = annual_energy_kwh * (electricity_rate_cents / 100)
Worked example
A 1,000-watt pump running 2 hours per day uses 2 kWh per day. Over 30 days, it uses 60 kWh. At 18.11 cents per kWh, the estimated pump electricity cost per month is $10.87. The default rate is a US residential planning estimate; replace it with your local usage-dependent rate. [1]
Calculation choices
Only usage-dependent electricity charges belong in the rate. Fixed monthly customer, meter, and connection charges are excluded because pump run time does not change them. Costs are estimates because pump power and daily run time can vary in real operation.