What is Total Dynamic Head (TDH)?

TDH is the total equivalent height a pump must push water against. This calculator includes static elevation head and Hazen-Williams friction losses for the pipe and listed fittings. It does not separately add velocity head, pressure head, or unsupported minor losses; include those when required by your system design. Pump manufacturers rate 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

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 = 10.44 × L × Q^1.852 / (C^1.852 × D^4.87)

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

HP = (TDH × GPM) / (3960 × 0.60)

Summary

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

How it works

Enter the vertical elevation rise the pump must overcome (static head).
Input total pipe run length, pipe diameter, and flow rate.
Select pipe material — PVC (C=150), copper (C=130), or galvanized steel (C=100) — which sets the Hazen-Williams friction coefficient.
Add the count of 90° elbows and gate valves; each converts to an equivalent pipe length to include in friction loss.
Friction head loss is computed with the US customary Hazen-Williams formula: h_f = 10.44 × L × Q^1.852 / (C^1.852 × D^4.87).
TDH = Static Head + Friction Head. A rough HP guide is derived from TDH × GPM ÷ 3960 ÷ pump efficiency (assumed 0.6).

Use cases

Size a booster pump for a residential water supply system.
Determine the pump needed for a drip-irrigation or sprinkler system.
Verify an HVAC chilled-water or hot-water circulating pump against the system curve.
Estimate friction losses when replacing an existing pump or upsizing pipe.
Check whether a submersible well pump can deliver adequate flow at the required head.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu