Well Pump Size Calculator
GPM and total dynamic head for sizing a well pump.
Enter your values
Enter the fixtures in the home you are working with.
Enter the pumping water level in ft.
Enter the elevation to tank in ft.
Enter the system pressure in psi.
Enter the friction loss in ft.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- 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
At a glance
| What it does | GPM and total dynamic head for sizing a well pump. |
|---|---|
| Category | Home & DIY |
| Inputs needed | Fixtures in the home, Pumping water level, Elevation to tank, System pressure, Friction loss |
| Main output | Required flow |
| Formula | TDH = depth + lift + 2.31 x psi + friction |
| Cost | Free — no sign-up, no download |
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.
Inputs explained
- Fixtures in the home
- Enter the fixtures in the home you are working with.
- Pumping water level(ft)
- Enter the pumping water level in ft.
- Elevation to tank(ft)
- Enter the elevation to tank in ft.
- System pressure(psi)
- Enter the system pressure in psi.
- Friction loss(ft)
- Enter the friction loss in ft.
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.
What do I need to enter into the Well Pump Size Calculator?
Just 5 values: fixtures in the home, pumping water level, elevation to tank, system pressure, friction loss. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Well Pump Size Calculator work out the answer?
Sizing needs two numbers: peak flow demand in GPM, and total dynamic head = pumping depth + elevation + pressure head + friction loss. It applies the formula TDH = depth + lift + 2.31 x psi + friction and shows the working so you can check each step by hand.
Is the Well Pump Size Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.