Convert a discharge gauge pressure directly to head, or build up pump head from elevation, friction loss, and velocity head — get hydraulic power in one shot.
Choose how you want to work out the pump head.
Reading taken directly from a pressure gauge on the pump discharge line.
Velocity in the discharge pipe, used to find the velocity head component.
Power Estimate (optional)
Head to match against the pump's performance curve
Enter your values and hit calculate to see the shaft power estimate.
Pump head is the amount of energy a pump imparts to a fluid, expressed as an equivalent height of water column rather than as a pressure — this is the standard convention used across pump manufacturer catalogues and referenced throughout the Hydraulic Institute's pump standards and general fluid mechanics texts such as Cengel & Cimbala's Fluid Mechanics: Fundamentals and Applications. Expressing energy as head rather than pressure has a practical advantage: the same pump curve applies regardless of the fluid's density, since head is purely a function of the pump's mechanical work, while pressure is not.
This calculator supports two common ways engineers arrive at head. The first, Pressure → Head, is used when a system is already running and a pressure gauge is mounted on the discharge line — this is the fastest way to check an installed pump against its rated performance curve. The conversion uses the standard relationship Head (m) = Pressure (bar) × 10.197, derived from the density of water and gravitational acceleration, and is the same conversion factor published by references such as the Engineering ToolBox pressure-to-head converter.
The second method, Elevation + Friction → Head, is used at the design stage, before a pump is even installed, when the physical layout of the piping system is known but no pressure gauge exists yet. Here the total head a pump must generate is built from three physical components: the static elevation the water must be lifted vertically, the friction loss from resistance inside the pipe, fittings, and valves along the route, and the velocity head, a small but real term representing the kinetic energy needed to keep the water moving at its discharge velocity, calculated as hv = V² ÷ (2 × g) with g = 9.81 m/s². Adding these three terms gives the head the pump must be rated for: Head = Elevation + Friction Loss + Velocity Head.
Once head and flow rate are known, the hydraulic power the pump imparts to the fluid is P(kW) = (Q × H × ρ × g) ÷ 3,600,000, with Q in m³/hr, H in metres, and ρ = 1000 kg/m³ for water. Dividing by the pump's overall efficiency gives the shaft power the driving motor must deliver, which is what determines the correct motor rating for the installation.
As with any sizing calculator, treat the output as an engineering estimate. Real friction loss depends on exact pipe condition, fitting count, and water temperature, so always confirm final figures against as-built drawings or a live pressure reading, and check the result against the selected pump's published head-versus-flow curve before purchase.
Head is independent of fluid density, so the same pump performance curve applies whether you're pumping water, a chemical solution, or any other liquid of a different density. Pressure, on the other hand, changes with fluid density for the same amount of pump work, which is why manufacturers rate pumps in head rather than pressure.
They describe the same underlying quantity — the total energy the pump must supply, in metres of head. "TDH" typically refers to the full system-side calculation including separate suction and discharge friction terms, while "pump head" is often used more loosely, including as a quick pressure-gauge conversion. Use the dedicated TDH calculator when you need a detailed suction/discharge breakdown.
At typical discharge velocities of 1–3 m/s, velocity head is usually only a few centimetres and is often neglected in quick hand calculations. It is included here for completeness and becomes more significant in smaller-diameter, higher-velocity pipe runs.
The 10.197 conversion factor is exact for pure water at standard conditions. For fluids of different density, or water at significantly different temperatures, the equivalent head will differ slightly since head is inversely related to fluid density for a given pressure.
Take the calculated head and your required flow rate, then choose a pump whose published head-versus-flow performance curve passes through or above that point, ideally near its best efficiency point (BEP). Use the shaft power figure to confirm the driving motor has adequate rated capacity.