Pump Head Calculator
Calculate total dynamic head for pump selection from static head, friction, and velocity. Enter values for instant results with step-by-step formulas.
Formula
TDH = Static Head + Friction Head + Velocity Head + Pressure Head
Where Static Head is the vertical elevation difference in feet, Friction Head includes pipe friction (Darcy-Weisbach) and fitting losses, Velocity Head = v^2/(2g), and Pressure Head converts any pressure differential to feet of head (psi x 2.31). TDH is used to size pumps and calculate required horsepower.
Worked Examples
Example 1: Municipal Water Booster Pump
Problem: Calculate TDH for a system with 25 ft static head, 200 ft pipe (6-inch diameter), 400 GPM flow, friction factor 0.018, 8 ft fittings loss, and 10 psi pressure differential.
Solution: Pipe area = PI x (0.5/2)^2 = 0.1963 ft2\nVelocity = (400/448.831) / 0.1963 = 4.54 ft/s\nVelocity head = 4.54^2 / (2 x 32.174) = 0.320 ft\nFriction head (pipe) = 0.018 x (200/0.5) x 0.320 = 2.304 ft\nTotal friction = 2.304 + 8 = 10.304 ft\nPressure head = 10 x 2.31 = 23.1 ft\nTDH = 25 + 10.304 + 0.320 + 23.1 = 58.72 ft
Result: TDH: 58.72 ft | Hydraulic HP: 5.93 | Brake HP: 8.47 (at 70% efficiency)
Example 2: Industrial Process Pump Sizing
Problem: Calculate TDH for 15 ft static head, 100 ft pipe (4-inch diameter), 200 GPM flow, friction factor 0.02, 5 ft fittings loss, no pressure differential.
Solution: Pipe area = PI x (0.333/2)^2 = 0.0873 ft2\nVelocity = (200/448.831) / 0.0873 = 5.10 ft/s\nVelocity head = 5.10^2 / (2 x 32.174) = 0.405 ft\nFriction head (pipe) = 0.02 x (100/0.333) x 0.405 = 2.432 ft\nTotal friction = 2.432 + 5 = 7.432 ft\nTDH = 15 + 7.432 + 0.405 + 0 = 22.84 ft
Result: TDH: 22.84 ft | Hydraulic HP: 1.15 | Brake HP: 1.65 (at 70% efficiency)
Frequently Asked Questions
What is Total Dynamic Head (TDH) and why is it critical for pump selection?
Total Dynamic Head (TDH) represents the total equivalent height that a pump must deliver fluid against, combining all resistances in the piping system. It is the single most important parameter for pump selection because it determines the energy the pump must impart to the fluid. TDH consists of four components: static head (the vertical elevation difference between source and destination), friction head (energy lost due to pipe wall friction and fittings), velocity head (kinetic energy needed to move the fluid), and pressure head (additional head required to overcome pressure differences). If you underestimate TDH, the pump will not deliver sufficient flow. If you overestimate it, you will select an oversized pump that wastes energy and may operate inefficiently off its best efficiency point.
How is friction head loss calculated in a piping system?
Friction head loss is calculated using the Darcy-Weisbach equation: hf = f x (L/D) x (v-squared / 2g), where f is the Darcy friction factor, L is the pipe length, D is the pipe internal diameter, v is the fluid velocity, and g is gravitational acceleration. The friction factor depends on the Reynolds number (which indicates whether flow is laminar or turbulent) and the pipe relative roughness. For turbulent flow in commercial pipes, the Moody chart or Colebrook-White equation is used to determine f, which typically ranges from 0.01 to 0.05. Additionally, fittings such as elbows, tees, valves, and reducers add equivalent length or minor losses to the total friction head. These losses are often significant and can account for 30 to 50 percent of the total friction losses in complex piping systems.
What is NPSH and why does it matter for pump operation?
Net Positive Suction Head (NPSH) is the absolute pressure available at the pump suction minus the vapor pressure of the fluid, expressed in feet of head. There are two NPSH values: NPSH Available (NPSHa), which is determined by the system design, and NPSH Required (NPSHr), which is specified by the pump manufacturer. For safe operation, NPSHa must always exceed NPSHr by a sufficient margin, typically at least 2 to 3 feet. If NPSHa falls below NPSHr, cavitation occurs, which is the formation and violent collapse of vapor bubbles inside the pump. Cavitation causes noise, vibration, reduced performance, and progressive damage to impeller surfaces. Factors that reduce NPSHa include high elevation, hot fluid temperatures, long suction pipe runs, and high suction-side friction losses.
Is my data stored or sent to a server?
No. All calculations run entirely in your browser using JavaScript. No data you enter is ever transmitted to any server or stored anywhere. Your inputs remain completely private.
How do I interpret the result?
Results are displayed with a label and unit to help you understand the output. Many calculators include a short explanation or classification below the result (for example, a BMI category or risk level). Refer to the worked examples section on this page for real-world context.
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