Pump Selection & Total Dynamic Head Calculator

Compute total dynamic head from static, friction, pressure, and velocity head, then size the pump by hydraulic and shaft horsepower using embedded fitting and fluid data.

System Inputs

💧 Pump Hydraulics

Flow Rate (gpm)

Fluid

Specific Gravity

Pump Efficiency (%)

Suction Static Head (ft)

Flooded suction: positive. Lift below pump: negative.

Discharge Static Head (ft)

Elevation of discharge point above pump centerline.

Suction Pressure (psi)

Discharge Pressure (psi)

Pipe Internal Diameter (in)

Total Straight Pipe Length (ft)

Friction Method

Hazen–Williams C

Fittings & Valves (quantities)

Pump Sizing Results

Total Dynamic Head

—

feet of liquid

Static Head

—

discharge − suction

Friction Head

—

pipe + fittings

Hydraulic Power

—

water horsepower

Shaft Power

—

at pump efficiency

Recommended Motor

—

next standard size

Formula Breakdown

Waiting for input…

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Fitting & Valve K-Factor Reference

Standard minor-loss coefficients (K) used in the fitting-head calculation.

Fitting / Valve	K Factor

Informative Guides & Helper Articles

Guide to Total Dynamic Head Calculation

Learn how static, friction, pressure, and velocity head combine into total dynamic head and drive pump horsepower.

Read Article →

How to Use the Pump Selection TDH Calculator

Computes total dynamic head from static lift and friction, then checks the operating point against curves.

Enter static head (suction condition + discharge elevation).
Enter pipe/fitting friction at design flow.
Read TDH duty point; overlay candidate curves.

TDH = Static + Friction

TDH = static + friction

TDH = static + friction: the unchanging lift plus losses that grow with flow squared. A pump is selected at one duty point where its curve meets the system curve - oversizing pushes operation left of BEP, where radial loads kill seals. The check preventing the classic startup failure: NPSH available > required + 0.5-1 m margin - hot liquid, altitude, long suction lines, throttled suctions are the four cavitation makers; cavitation sounds like pumping gravel because it is.

Pump Selection TDH Calculator FAQ

What is total dynamic head?

Static lift plus friction at design flow; friction grows with flow squared, bending the system curve upward.

Why not oversize the pump?

Operating far left of BEP causes recirculation and radial loads that eat seals. Margin belongs in NPSH, not size.

What is NPSH?

Net positive suction head. Starve the impeller (hot fluid, altitude, suction throttling) and cavitation destroys it.