Free Well Pump Sizing Calculator
Size a submersible well pump by computing horsepower from flow rate and total dynamic head.
GPM
ft
%
Brake Horsepower
0.84 HP
Water Horsepower0.505 HP
Motor Power628 W
Brake Horsepower vs Required Flow Rate
Well Pump Sizing
Water HP = GPM x TDH / 3960
Brake HP = Water HP / Efficiency
The constant 3960 comes from converting GPM and feet of head to horsepower units. Submersible pump efficiency is typically 50 to 70 percent. Multiply HP by 746 to get watts.
Example Calculation
10 GPM pump with 200 ft TDH, 60% efficiency.
- 01Water HP = 10 x 200 / 3960 = 0.505 HP
- 02Brake HP = 0.505 / 0.60 = 0.84 HP
- 03Motor = 0.84 x 746 = 627 W
- 04Select a 1 HP submersible pump.
Frequently Asked Questions
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