What is Total Dynamic Head (TDH)?

TDH is the total equivalent height a pump must push water against — it combines static head (elevation difference), friction losses in the pipe and fittings, and, in high-velocity systems, a small velocity head component. Pump manufacturers rate their pumps against head in feet or meters.

Why does pipe material affect friction loss?

Different materials have different surface roughness. The Hazen-Williams coefficient C captures this: PVC is very smooth (C=150), copper is smooth (C=130), and galvanized steel is rougher (C=100). A lower C means more friction and higher head loss.

How accurate is this calculator?

It uses the standard Hazen-Williams equation, which is accurate for turbulent water flow (not suitable for gases or very viscous fluids). Real systems may have minor losses from tees, reducers, and check valves that are not included here; add 10–20% safety margin when selecting a pump.

What does the HP recommendation mean?

The guide formula is HP = (TDH × GPM) / (3960 × efficiency), assuming ~60% pump efficiency. It gives a rough starting class. Always verify against the pump manufacturer's performance curve at your actual flow rate.

Should I include pipe fittings other than elbows and gate valves?

This tool covers the two most common fitting types. For systems with tees, swing check valves, or globe valves, add their equivalent pipe lengths manually: a fully open globe valve adds roughly 20× its pipe diameter in equivalent length.

Pump Head Calculator

Name: Pump Head Calculator
Availability: InStock
Author: Nham Vu

Calculate Total Dynamic Head (TDH) to size a water pump for plumbing, irrigation, or HVAC. Enter elevation, pipe length, diameter, flow rate, and fittings.

System Parameters

Elevation Rise (ft)

Vertical height water must be pumped

Total Pipe Length (ft)

Pipe Diameter (inches)

Flow Rate (GPM)

Pipe Material

90° Elbows

Gate Valves

Total Dynamic Head (TDH)

— ft

Enter values and click Calculate

Static Head

—

Friction Head

—

Pump HP Class

—

horsepower (guide)

Formula Reference

h_f = 10.67 × L × Q^1.852 / (C^1.852 × D^4.87)

L = pipe length (ft), Q = flow (GPM), C = Hazen-Williams coeff., D = diameter (ft)

HP = (TDH × GPM) / (3960 × 0.60)

Summary