Pump TDH Calculator
The Pump TDH Calculator sizes a pump and motor from Total Dynamic Head (TDH) = static head + friction head + velocity head. Example: for a 200 L/min pump lifting water 15 m through 60 m of 50 mm PVC pipe, Total Dynamic Head = 18.12 m, Pipe velocity = 1.54 m/s, Recommended motor = 1.1 kW, NPSH available = 9.44 m (per ISO 9906 | PSME Code | ASHRAE 2021 Ch.22).
How it works
TDH = H_static + H_friction + H_velocity, where friction head uses Darcy–Weisbach with the Colebrook–White friction factor and real water properties at the operating temperature.
Worked example (Plumbing & Pumps)
Inputs: a 200 L/min pump lifting water 15 m through 60 m of 50 mm PVC pipe.
| Result | Value |
|---|---|
| Total Dynamic Head | 18.12 m |
| Pipe velocity | 1.54 m/s |
| Recommended motor | 1.1 kW |
| NPSH available | 9.44 m |
Computed live by WorkHive's calculation engine; standard: ISO 9906 | PSME Code | ASHRAE 2021 Ch.22.
How to use this calculator
- Enter the figures for the duty you are sizing: the worked example below uses a 200 L/min pump lifting water 15 m through 60 m of 50 mm PVC pipe.
- The calculator returns Total Dynamic Head, Pipe velocity, Recommended motor, NPSH available, computed per ISO 9906 | PSME Code | ASHRAE 2021 Ch.22.
- Check the worked example to confirm the method matches how you would do it by hand, then run your own numbers in the interactive tool.
FAQ
What is total dynamic head (TDH)?
TDH is the total equivalent height a pump must overcome: the static lift plus friction losses in the pipe plus the velocity head. It sets the pump and motor size.
How do I calculate pump head?
Add static head + friction head + velocity head. Friction head comes from the Darcy–Weisbach equation using the Colebrook–White friction factor for the pipe material and flow.
What motor size do I need for a 200 L/min pump?
For a typical 200 L/min duty at ~18 m TDH, a 1.1 kW (1.5 HP) motor is usually enough after applying pump and motor efficiency and a service-factor margin. Always confirm against the manufacturer curve.
What is NPSH available and why does it matter?
NPSH available is the suction-side pressure margin before cavitation. It must exceed the pump's NPSH required, or the pump cavitates and wears out. It falls with elevation and hot water.
Run it on your own numbers
Open the interactive Pump TDH Calculator in WorkHive: free, no sign-up needed for the calculators.