Well Pump Calculator
Calculate well pump horsepower from well depth, water level, discharge pressure, and desired flow rate.
Results
Visualization
How It Works
Well pump sizing uses Total Dynamic Head (TDH) — the sum of lift, pressure, and friction losses. The pump must overcome all three to deliver water at the desired flow and pressure.
The Formula
HP = (GPM x TDH) / (3960 x Efficiency)
TDH = Pumping Level + Pressure Head + Friction Loss
TDH = Pumping Level + Pressure Head + Friction Loss
Variables
- TDH — Total Dynamic Head — total resistance in feet
- 3960 — Constant converting GPM x ft to HP
- 2.31 — Feet of head per PSI
Worked Example
200 ft well, 80 ft water level, 50 PSI, 10 GPM: TDH = 88 + 115.5 + 1.76 = 205 ft. HP = (10 x 205)/(3960 x 0.55) = 0.94 HP. Use 1 HP submersible.
Practical Tips
- Always round up to the next standard HP size
- Submersible pumps are required for wells deeper than 25 ft water level
- Variable speed pumps save energy and reduce water hammer
- Include a check valve every 100 ft of vertical lift