Pump Head Calculator
Pressure into metres of head, the velocity head beside it, and the TDH reminder that the pump carries all three kinds.
Pump Head Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Gauge pressure; static conversion only
- No NPSH or vapour-pressure model
In short: A 3 bar discharge on water reads 30.581040 m of head — H = p/(ρ·g) = 300,000 Pa ÷ 9,810 — and the rule of thumb falls out for free: every 100 kPa is 10.193680 m of water. Beside it sits the kinetic share: at 2 m/s the velocity head is 0.203874 m, small but compoundable. Head is the pump's native language because it is fluid-independent energy per weight — the same curve lifts mercury and wine, only the pressure disagrees.
Formula
H = p/(ρ·g) ··· hᵥ = v²/2g
Head is pressure expressed as the height of fluid column that would produce it — energy per unit weight, the one currency every gravitational pump calculation spends. Dividing by ρg converts pascals to metres; the velocity head prices the kinetic share of total dynamic head, the term most home-brew pump sums forget.
Worked Example
- Enter the gauge pressure.
- Enter the fluid density.
- Read the head in metres.
- Check the velocity head for the TDH sum.
Defaults: 300 kPa on water → 30.581039 m; velocity head 0.203874 m at 2 m/s. The 1 bar check: 100 kPa → 10.193680 m — the rule of thumb every fireman knows as roughly ten metres per bar.
Strengths & Limits Of This Model
Where this engine is strong
- Velocity head priced beside the static
- The 100 kPa ≈ 10 m rule derived
Where it stops
- No suction-side analysis
- No friction share (see pressure drop)
Practical Use Cases
Pump spec sheets
pressure duty to head duty
TDH assembly
the pressure share of the sum
Teaching
why curves are drawn in metres
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Pump Head Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
Why do pump curves use metres instead of pressure?
Because head is fluid-independent: a pump that lifts water 30 m would lift mercury 30 m too — only the pressure (and the motor's screaming) would differ. Metres of head describe what the pump DOES; pascals describe what one particular fluid FEELS. Curves in metres let one casting serve a hundred fluids, which is why the conversion on this page is the industry's daily bread.
Is gauge or absolute pressure correct here?
Gauge — the pump adds head ABOVE atmospheric, and the atmosphere is already balanced on both sides of the suction and discharge gauges. Using absolute pressure silently adds a 10.193680 m head of atmosphere to every answer. The one exception is NPSH calculations on the suction side, where absolute is king and vapour pressure joins the table.
What is total dynamic head, exactly?
The whole bill the pump pays: static lift (the height), friction losses (the pipe's toll), pressure head (the destination's gauge) and the velocity head difference. The classic worked example climbs 12 m static to 16.7 m TDH once friction and discharge pressure join. This page prices the pressure and kinetic shares; the pressure drop page prices the friction share.
Why is the velocity head so small?
At ordinary pipe velocities (1–3 m/s) the kinetic term is centimetres to a decimetre of head — next to tens of metres of static lift it is rounding error. It matters at the pump's own flanges (where velocities are high), in nozzles, and whenever two measurements compete at the fourth significant figure. The card exists because forgetting it is cheap at 2 m/s and expensive at 12.
Does the fluid density affect the pump's head?
The head NO, the pressure YES: a centrifugal pump produces the same metres for any fluid, but heavy fluids arrive with proportionally more pressure behind them. That is why seawater duties read higher discharge pressures on the same pump. The ρ in this page's divisor is how the two currencies convert.
How does suction lift enter?
As negative static head: a pump standing above its wet well must FIRST lift the suction column, and every metre of lift spends about 10.193680 kPa of the atmosphere's 101.325 allowance. Too much suction lift and the water boils at room temperature — cavitation, the pump's way of filing a grievance. TDH counts both columns honestly.
Why is every 100 kPa about 10 metres on water?
Because 100,000 Pa ÷ (1,000 × 9.81) = 10.193680 m — the exact arithmetic behind the fireman's rule of thumb. The atmosphere itself weighs exactly one bar, which is why lift pumps die near ten metres: beyond that you are asking the sky to push harder than it does. The conversion card is this page's most quotable line.
Where does the velocity head matter most?
At transitions: pump nozzles, orifice plates, and any place the flow area changes sharply — the velocity head there is real money, feeding both the kinetic term and the turbulence losses that follow it. Inside long uniform pipes it cancels between sections. Bernoulli keeps the account; friction and area changes spend it.