Pump Head Calculator (TDH)

The Pump Head Calculator computes Total Dynamic Head (TDH = static + friction + velocity + pressure head) with Hazen-Williams friction loss, fitting equivalent lengths, and pump power in HP/kW. It includes an interactive SVG system curve chart and NPSH available calculation — free, no signup required.

System Parameters

Suction Level (m)

Discharge Level (m)

Pipe Inner Diameter (mm)

Pipe Length (m)

Pipe Material

Flow Rate (L/min)

Pump Efficiency (%)

Discharge Pressure (kPa)

Pipe Fittings

Fitting Equivalent Length Reference

Fitting	L/D
90° Elbow (standard)	30
90° Elbow (long radius)	20
45° Elbow	16
Tee (straight-through)	20
Tee (branch flow)	60
Gate Valve (full open)	8
Globe Valve (full open)	340
Check Valve (swing)	100
Check Valve (lift)	600
Ball Valve (full open)	3
Butterfly Valve (full open)	45
Entrance (sharp-edged)	25
Exit (pipe to tank)	50
Union / Coupling	2
Reducer	10

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What is Total Dynamic Head (TDH)?

Total Dynamic Head (TDH) is the total equivalent height that a pump must overcome to move fluid through a system. TDH = Static Head + Friction Head + Velocity Head + Pressure Head. Static head is the vertical distance between the water source and discharge point. Friction head accounts for energy lost due to pipe wall friction and fittings (elbows, valves, tees). The Hazen-Williams equation (h = 10.67 × Q^1.852 / (C^1.852 × D^4.87) × L) is the standard method for calculating friction losses in water piping. Pump power in HP = (Q × TDH × ρ × g) / (η × 746), where η is pump efficiency.

How to Use This Calculator

Enter the suction and discharge elevations to calculate static head
Specify the pipe diameter, length, and material for friction loss calculation
Add pipe fittings (90° elbows, tees, gate valves, check valves) with quantities
Enter the desired flow rate and estimated pump efficiency
Click Calculate to see the TDH breakdown, required pump power, and system curve chart

Frequently Asked Questions

How do I determine static head for my pump?

Static head is the vertical distance from the water surface at the suction point to the discharge point. For a well pump, it is the distance from the water table to the highest discharge point. For a booster pump, it is the height difference between the inlet and outlet. Static head does not depend on pipe length or fittings — only vertical elevation change.

What is the equivalent length method for fitting losses?

The equivalent length method converts each fitting to an equivalent length of straight pipe that would produce the same friction loss. For example, a 90° standard elbow has an L/D ratio of about 30, meaning it equals 30 pipe diameters of straight pipe. A gate valve (fully open) is about 8 L/D. This method simplifies the calculation by adding equivalent lengths to the total pipe length.

What pump efficiency should I use?

Typical centrifugal pump efficiencies range from 60% to 85% at the best efficiency point (BEP). Small residential pumps: 50–65%. Medium commercial pumps: 70–80%. Large industrial pumps: 75–85%. Use 70% as a conservative starting estimate if the actual pump curve is unknown. Operating far from BEP reduces efficiency significantly.