About this calculator
Total Dynamic Head (TDH) is the total resistance a pump must overcome — elevation change, friction losses in pipework and fittings, and any required residual discharge pressure. This calculator adds these components together, converting discharge pressure to metres of head (1 bar ≈ 10.2 m of water).
Formula
TDH (m) = Static Head + Friction Loss + (Discharge Pressure × 10.2)
- Static HeadElevation difference between source and discharge — metres
- Friction LossPipe, fitting and valve losses — metres
- Discharge PressureRequired pressure at outlet, if any — bar
- TDHTotal Dynamic Head — metres
Worked Example
Given: A pump lifts water 15m with an estimated 3m of friction loss, and needs 0 bar residual discharge pressure.
Result: TDH = 15 + 3 + 0 = 18 m.
How to Use
- Enter the static head — the vertical elevation difference between the water source and the discharge point.
- Enter the estimated friction loss through pipes, fittings and valves (from a pipe friction loss chart for your flow rate, pipe size and length).
- If the application needs residual pressure at the outlet (e.g. a sprinkler or nozzle), enter it in bar; otherwise leave at 0.
- Click Calculate to get total dynamic head in metres.
Important Assumptions
- Friction loss must be estimated separately (from pipe friction charts for the specific pipe diameter, material, length and flow) and entered as an input — it is not calculated internally here.
- Uses the standard approximation 1 bar ≈ 10.2 m of water head.
Common Mistakes
- Sizing a pump using static head alone and ignoring friction losses, which is one of the most common pump undersizing mistakes.
- Forgetting to include suction-side losses if the pump lifts water from below its own level.
Frequently Asked Questions
How do I estimate friction loss?
Use a pipe friction loss chart or the Hazen-Williams/Darcy-Weisbach equation for your specific pipe material, diameter, length and flow rate — friction loss charts from pipe manufacturers are the quickest practical source.
Why convert discharge pressure to metres of head?
Because pump performance curves are almost always plotted in metres of head, so all resistance components need to be expressed in the same unit before adding them together.
These calculators are provided for informational and estimation purposes. Results depend on the assumptions and input values used. Always verify critical engineering calculations against applicable standards, manufacturer specifications, site measurements, and qualified professional advice.