What does your water pump use?
Convert horsepower to watts, then account for the time your motor actually runs.
Rates as per TNPDCL, October 2026Start with horsepower
This estimator uses 1 HP = 746 W. A 1 HP pump, used one hour a day for 30 days, gives 22.38 kWh per month. The two-month estimate is 44.76 kWh before rounding.
A motor’s HP rating can refer to mechanical shaft output. Electrical input is higher when motor losses are included. Use the electrical input watts on the label, or measured energy use, when available.
Use volts and amps instead
For a single-phase load, watts = volts × amps × power factor. At 230 V, 5 A and a power factor of 0.9, input power is 1,035 W. One hour daily for 30 days gives 31.05 kWh.
The default power factor of 0.9 is an editable estimate. Enter the rated or measured value if you know it. This formula is not a three-phase motor calculation.
Enter actual running time
Use the combined daily runtime. For example, two 15-minute runs equal 0.5 hours per day. Keep compressor on-time at 100% for a pump; the hours already describe when it is running.
Calculate the household total
Add your pump alongside the other appliances. Electricity costs depend on the home’s total units and subsidy branch. A pump does not receive its own free-unit allowance.
Check your final estimate against the official TNPDCL calculator using the rounded two-month units.
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