Well Pump Size Calculator
GPM and total dynamic head for sizing a well pump.
Enter your values
ⓘ Live results
Results
- Required flow
- 10.2 GPM
- Total dynamic head
- 266 ft
- Approx pump power
- 1.14 HP (choose 1.5 HP)
- Pressure head
- 116 ft
Working
- 1TDH = 120 + 20 + 116 + 10 = 266 ft
Quick answer
Sizing needs two numbers: peak flow demand in GPM, and total dynamic head = pumping depth + elevation + pressure head + friction loss.
TDH = depth + lift + 2.31 x psi + friction
How to use the Well Pump Size Calculator
- 1Count fixtures to estimate peak demand, or use your known GPM requirement.
- 2Measure the pumping water level, not the static level - drawdown matters.
- 3Add 2.31 ft of head for every psi of system pressure you want at the tank.
Worked example
Using the values the calculator loads with:
Inputs
- Fixtures in the home12
- Pumping water level120 ft
- Elevation to tank20 ft
- System pressure50 psi
- Friction loss10 ft
Results
- Required flow10.2 GPM
- Total dynamic head266 ft
- Approx pump power1.14 HP (choose 1.5 HP)
- Pressure head116 ft
- TDH = 120 + 20 + 116 + 10 = 266 ft
Frequently asked questions
What GPM does a house need?
A typical 3-bed home peaks around 8 to 12 GPM. Larger homes with irrigation can need 15 to 25 GPM.
Why is total dynamic head so important?
A pump's flow drops as head rises. Pick the pump from its curve at your actual TDH, not from the headline GPM on the box.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.