Pump Head Calculator

It works out the total head a pump must produce to deliver your flow — adding the vertical lift, the friction lost in the pipe and fittings, and any pressure required at the outlet. The result, in feet of head together with the flow in GPM, is the duty point you take to a pump’s performance curve to choose the right model.

Total head = static lift + friction losses + pressure head. Static lift is the vertical distance from the source water surface to the discharge point. Friction is calculated from the flow, pipe bore, length and material (this tool uses the Hazen–Williams formula, with an allowance for fittings). Pressure head converts any required outlet pressure at about 2.31 ft per psi. Example: 40 ft (12 m) of lift plus 10 ft (3 m) of friction feeding an open tank is a 50 ft (15 m) total head.

The industry name for exactly this sum — the head the pump “feels” while actually pumping, as opposed to the static lift alone. It is dynamic because the friction part grows with flow: the same installation has a higher TDH at 16 GPM than at 8. Pump curves are drawn in TDH, which is why you size with it.

Find your duty point — the required flow at the calculated head — and pick a pump whose curve passes at or above it, ideally near the middle of the curve where efficiency peaks. Don’t buy on the “max head” printed on the box: that is the head at zero flow. A pump advertising 130 ft (40 m) max might deliver only a trickle at 100 ft (30 m).

Friction loss rises with roughly the fifth power of shrinking diameter — going one pipe size down can triple or quadruple the friction head at the same flow. If the calculated friction dominates your total, upsizing the delivery pipe is almost always cheaper than buying a bigger pump and paying its running costs forever.

A surface pump can only draw water up about 25 ft (7 m) of suction lift in practice (atmospheric pressure sets the limit) — deeper sources need a submersible or a pump lowered to the water. For wells and boreholes, measure the lift from the drawdown water level while pumping, not the pump’s installed depth. Deep or hot installations should also have the pump’s NPSH requirement checked.