Pump Head Calculator (Total Dynamic Head)
Calculate total dynamic head from static lift plus pipe friction loss using the Hazen-Williams equation, with flow velocity and pressure output.
Result
- Static head (lift)10.00 m
- Friction head loss1.04 m
- Flow velocity1.06 m/s
- Equivalent pressure108.3 kPa · 1.08 bar · 15.7 psi
Step-by-step
- Convert flow to m³/s: 500 L/min ÷ 60000 = 0.008333 m³/s.
- Convert diameter to m: 100 mm = 0.1 m; pipe area = π·(d/2)² = 0.007854 m².
- Friction loss (Hazen-Williams) = 10.67 · 100 · 0.008333^1.852 / (150^1.852 · 0.1^4.8704) = 1.04 m.
- Total dynamic head = static 10 m + friction 1.04 m = 11.04 m.
How to use this calculator
- Enter the static head — the vertical rise from the water source surface to the discharge point.
- Enter the total pipe length; add an equivalent-length allowance for elbows and valves.
- Enter the pipe inner diameter (mm) and the design flow rate (L/min).
- Pick the pipe material to set the Hazen-Williams C coefficient, then read total dynamic head and velocity.
About this calculator
Total dynamic head (TDH) is the total resistance a pump must overcome, expressed as an equivalent height of water column. It is the sum of the static head — the vertical distance the water is lifted — and the friction (or dynamic) head, the pressure lost to friction as water moves through pipe and fittings. This calculator computes friction loss with the Hazen-Williams equation, the industry-standard empirical formula for water in pressurised pipes, using a roughness coefficient C that depends on pipe material. It also reports the flow velocity (which should generally stay below ~1.5–2.5 m/s to limit losses and water hammer) and converts the head to pressure in kPa, bar, and psi. Use TDH to select a pump whose head-flow curve meets your duty point.
How it works — the formula
TDH = Static head + Friction head
Friction (Hazen-Williams, SI):
h_f = 10.67 · L · Q^1.852 / (C^1.852 · d^4.8704)
Pressure: ΔP = ρ · g · h (ρ=1000 kg/m³, g=9.80665 m/s²)Friction loss grows with the 1.852 power of flow and falls steeply with diameter (4.87 power), so modest pipe upsizing sharply cuts losses. Head in metres of water converts to pressure via the hydrostatic relation ΔP = ρgh.
Worked examples
- Inputs:
- staticHead=10, length=100, diameter=100, flow=500, cFactor=150
- Output:
- friction ≈ 1.04 m → TDH ≈ 11.04 m
- Inputs:
- staticHead=0, length=50, diameter=50, flow=200, cFactor=120
- Output:
- friction ≈ 4.22 m → TDH ≈ 4.22 m
- Inputs:
- staticHead=20, length=200, diameter=150, flow=1000, cFactor=130
- Output:
- friction ≈ 1.36 m → TDH ≈ 21.36 m
Limitations
- Valid for water near 15 °C in turbulent flow; not for gases or viscous fluids.
- Fittings must be added manually as equivalent pipe length.
- Does not include velocity head or suction-side NPSH considerations.
Engineering estimate. Confirm pump selection against the manufacturer's certified head-flow and NPSH curves.