Pump Total Dynamic Head Calculator
Pump total dynamic head (TDH) calculator. Adds static lift, friction loss, pressure head and velocity head to size a pump, in metres and feet. Educational only.
Pump Total Dynamic Head Calculator
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How to use the total dynamic head calculator
Enter the static lift
This is the vertical height the water must be raised, measured from the source water level to the point of discharge — pure elevation, independent of flow.
Add the friction loss
Enter the friction head lost in the pipework plus fittings at the design flow. Use the Hazen-Williams calculator for the pipe friction and add equivalent lengths for valves and bends.
Add pressure and velocity
If the outlet needs a residual pressure (e.g. for a sprinkler), enter it and pick the unit. Enter the flow velocity so the calculator can add the small velocity head.
Acknowledge, then read the TDH
The total dynamic head, in metres and feet, is what the pump must develop at your design flow. Use it with the flow rate to pick a pump from the manufacturer's curve.
Total dynamic head — what a pump really has to overcome
Four heads add up to one duty point
Choosing a pump comes down to two numbers: how much water it must move (the flow rate) and how much "head" it must develop to push that water where it needs to go. Head is energy expressed as an equivalent height of liquid, and the total a pump must overcome — the total dynamic head, or TDH — is the sum of four parts. The static head (or static lift) is the pure vertical distance the water is raised, from the source level to the discharge point; it doesn't change with flow. The friction head is the energy lost to friction in the pipes and fittings, and unlike static head it grows steeply with flow. The pressure head is any residual pressure required at the outlet — a hose nozzle, a sprinkler, or a pressurised tank — converted into an equivalent height of liquid. And the velocity head, v²/2g, is the kinetic energy of the moving water; it is usually small but completes the energy accounting. Add them and you have the head the pump must produce at the design flow.
The reason the breakdown matters is that the parts behave differently. Static and pressure heads are fixed for a given system, but friction head rises roughly with the square of flow, so the TDH is really a curve — the system curve — that climbs as you demand more flow. A pump is selected by overlaying its own head-versus-flow curve on this system curve; they intersect at the operating point, the flow and head the installed pump will actually deliver. Get the TDH wrong and the pump runs at the wrong point: undersize the head and it delivers less flow than needed; oversize it and the pump runs inefficiently, wastes energy, and may cavitate or wear prematurely.
"A pump doesn't just lift water — it overcomes elevation, friction, pressure, and motion all at once. Add those four heads and you have the single number that, with flow, picks the pump."
Estimating well, then selecting properly
This calculator adds the four heads to give a TDH in metres and feet, which is exactly the figure you plot against flow to read a pump curve. But a sound pump selection involves more than the headline number. Friction loss must be computed at the real design flow with all fittings included, and because it varies with flow you should think in terms of the whole system curve, not a single point. The available suction conditions matter too: the net positive suction head available (NPSHa) must exceed the pump's required NPSH to avoid cavitation, a check this tool does not perform. Real installations also consider efficiency at the operating point, motor sizing, variable-speed control, future demand, and the specific liquid's properties. Treat the TDH from this tool as an educational estimate and a starting point for selection; the final pump choice, suction analysis, and system design should be done with manufacturer pump curves and, for anything beyond a simple domestic case, a qualified engineer.
10 Facts About Total Dynamic Head
TDH = static + friction + pressure + velocity head.
Head is energy expressed as an equivalent height of liquid.
Static head is pure elevation — fixed with flow.
Friction head rises ~with the square of flow.
Velocity head = v²/(2g) — usually small.
1 bar ≈ 10.2 m of water; 1 psi ≈ 0.70 m.
TDH + flow set the pump's duty point on its curve.
The system curve rises as flow increases.
Oversizing wastes energy and risks cavitation.
Always also check NPSH on the suction side.
Frequently asked questions
Total dynamic head (TDH) is the total head a pump must develop to move water at the design flow, expressed as an equivalent height of liquid. It is the sum of the static lift (elevation), the friction head lost in the pipes and fittings, any required discharge pressure converted to head, and the velocity head (v²/2g). With the flow rate, the TDH is what you use to select a pump from its performance curve.
Static head is just the vertical distance the water is raised and doesn't change with flow. TDH is the complete picture: static head plus the friction head (which grows with flow), plus any pressure head needed at the outlet, plus the velocity head. A pump sized only for static head would fall short as soon as flow created friction losses, which is why TDH, not static head alone, governs pump selection.
For water, 1 bar is about 10.2 metres of head and 1 psi is about 0.70 metres (or 2.31 feet). The general relation is head = pressure ÷ (density × g). The calculator does this for you — choose whether your required discharge pressure is in metres of head, bar, or psi, and it converts to metres before adding it to the total. Other liquids with different densities convert differently.
Friction loss rises roughly with the square of the flow rate — push twice the water and friction head goes up about fourfold. That's why TDH isn't a single number but a curve (the system curve) that climbs with flow. You should compute the friction head at the actual design flow, and recognise that at higher flows the pump will have to develop more head. The static and pressure components, by contrast, stay constant.
Plot your design flow against the TDH on the pump manufacturer's head-versus-flow curve. The point where your system curve crosses the pump curve is the operating point — the flow and head the pump will actually deliver once installed. Choose a pump whose curve passes through (or just above) your required flow and head, ideally near its best-efficiency point, and verify the suction conditions separately.
Usually it's small — at 2 m/s the velocity head is only about 0.2 m — so in many systems it's a minor term. But it completes the energy balance and can matter in high-velocity or precise applications. The calculator includes it (v²/2g) so the total is complete. If you leave the velocity at zero it simply drops out, and the TDH is then the sum of static, friction, and pressure heads.
TDH is only the discharge-side requirement. On the suction side you must check that the net positive suction head available (NPSHa) comfortably exceeds the pump's required NPSH, or the pump will cavitate — vapour bubbles form and collapse, causing noise, vibration, lost performance, and damage. This calculator does not assess NPSH, so a complete pump selection must include a separate suction analysis, especially for high-lift or hot-liquid applications.
Use it for learning and a first estimate of the head a pump must develop. A proper selection uses manufacturer pump curves, the full system curve, NPSH analysis, efficiency, motor sizing, and the liquid's properties, and for anything beyond a simple domestic case should be done by a qualified engineer. Treat the TDH here as an educational estimate, not a final specification.
The head calculation in metres of liquid is general, but two things change for other liquids. The pressure-to-head conversion depends on density, so a denser liquid converts a given pressure into less head; and the friction loss you feed in must be computed for that liquid's viscosity, usually with Darcy-Weisbach rather than Hazen-Williams. The pressure of a pump in head is independent of density, but the power and the pressure in bar are not. For non-water liquids, work with a specialist and the fluid's actual properties.
No. The values you enter are processed entirely in your browser. Nothing is sent to a server, stored, or shared, and no account is required. The calculation runs on your device only.
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