Pump Head Calculator
Determine the total dynamic head and shaft power needed to move fluid through a piping system. Use this when sizing pumps for water supply, irrigation, HVAC, or industrial fluid transfer.
About this calculator
Total Dynamic Head (TDH) is the sum of static head, friction loss, and velocity head — all in metres of fluid column. Static head is the elevation difference the pump must overcome; friction loss accounts for pipe wall resistance; velocity head represents kinetic energy of the flowing fluid. Once TDH is known, shaft power (in kW) is calculated as: P = TDH × Q × ρg / η, where Q is flow rate (m³/s), ρg = 9810 N/m³ (specific weight of water), and η is pump efficiency as a decimal. The formula used here is: P (kW) = (staticHead + frictionLoss + velocityHead) × flowRate × 9810 / (pumpEfficiency / 100) / 1000. Selecting the correct pump requires knowing both TDH and the required power to avoid under- or over-sizing.
How to use
Suppose a pump must lift water 10 m (static head), overcomes 3 m of friction loss, and 0.5 m of velocity head, at a flow rate of 0.05 m³/s with 75% efficiency. TDH = 10 + 3 + 0.5 = 13.5 m. Power = (13.5 × 0.05 × 9810) / (75 / 100) / 1000 = 6,621.75 / 0.75 / 1000 = 8.83 kW. This means you need a pump delivering at least 8.83 kW of shaft power to move the fluid under these conditions.
Frequently asked questions
What is total dynamic head and why does it matter for pump selection?
Total dynamic head (TDH) is the total equivalent height that a pump must push fluid against, expressed in metres. It combines static head (elevation change), friction losses (pipe resistance), and velocity head (kinetic energy). TDH is critical because pump manufacturers rate their equipment on head-vs-flow curves, so knowing your TDH lets you match the pump to the system operating point. An undersized pump will fail to deliver the required flow rate, while an oversized one wastes energy.
How does pump efficiency affect the power required to move fluid?
Pump efficiency represents how much of the input shaft power is actually converted into useful fluid energy. A pump at 75% efficiency uses 33% more power than a theoretically perfect 100% efficient pump for the same TDH and flow. In the formula P = TDH × Q × 9810 / η, a lower η directly increases required power. Real-world centrifugal pumps typically run between 60–85% efficiency at their best efficiency point (BEP), so always obtain the efficiency from the pump's performance curve at your operating conditions.
What is the difference between static head and friction loss in a pump system?
Static head is the fixed elevation difference between the fluid source and the discharge point — it does not change with flow rate. Friction loss, by contrast, is caused by fluid viscosity and pipe wall roughness resisting flow, and it increases with the square of velocity (and therefore flow rate). In a real system, friction loss can dominate at high flow rates, so it must be calculated carefully using methods like the Darcy-Weisbach equation. Together they form the system curve that the pump must overcome.