- Attach your pump to the water source using the hose.
- Make sure the pump's nozzle is facing as vertical as is possible. You will be measuring the height that it achieves, and this is less accurate a measure of "pump head," the measurement you will be converting from, if the expulsion from the pump is not vertical (and thus the distance it achieves is altered by the difference in gravitational effects).
- Open the valve of the pump, and let it run for a few moments, to achieve its standard height.
- Measure the distance from the pump nozzle to the height achieved by the expulsion. This number is the "pump head."
- Divide the "pump head" in feet by .43 to determine the pump's pressure in psi, that is, pounds per square inch.
How to Calculate Pump Pressure
There are a number of contexts where the calculation of pump pressure can be key to minimizing expenditure and maximizing safety. Unfortunately, there are a number of factors that can go into the pressure experienced by a pump, from the input pressure to the design of the pump itself. Depending on the type of pump in question -- a deviance in the expected pressure in an aquarium pump is far less damaging than a home water pump -- the calculation can be more or less delicate.