Pump Sizing Calculator
Calculate total dynamic head from lift, friction and pressure.
How this calculator works
TDH = static lift + (pipe length × friction ÷ 100) + (psi × 2.31)
One psi equals 2.31 feet of head for water. Pump curves plot flow against head, so you select a pump by finding where your required flow and TDH intersect on its curve.
Worked example
With static lift 50 ft, total pipe length 200 ft, friction loss per 100 ft 3 ft, required pressure at outlet 40 , this calculator returns 148.4 ft.
Frequently asked questions
What is total dynamic head?
The total resistance a pump must overcome: the vertical lift, plus friction losses in the pipe, plus any pressure required at the outlet. It is the number you match against the pump curve.
How do I convert PSI to feet of head?
Multiply by 2.31 for water. Forty psi at the outlet is equivalent to 92.4 ft of head, which on most residential systems is the largest single component of TDH.
Does pipe size affect pump sizing?
Substantially, through friction. Going up one pipe size can cut friction loss by half or more, which often lets you fit a smaller pump — usually cheaper than the larger pump over the system lifetime.
What happens if a pump is oversized?
It runs off the right-hand end of its curve, cavitates, wastes energy and wears the impeller and seals. Pumps are efficient only near their best efficiency point, so accurate TDH matters both ways.