Look along the y-axis. This is the vertical axis on the graph. This axis measures the feet header which is the unit of measurement used to for the power supplied to a water pump. Feet header measurements increase as you move up the y-axis. Sometimes the y-axis is labeled "head."

Look at the x-axis. This is the horizontal axis on the graph. This axis measures water flow. Water flow increases as you move to the right on the x-axis. Sometimes the x-axis is labeled "capacity."

Find a point on the pump curve and find the corresponding numbers on the y-axis and the x-axis. You can do this by lining up the point with your index fingers or, if you need a more precise reading, use a ruler and a pencil to mark the exact location of the point along the y-axis and x-axis.

Multiply the numbers along the y-axis by 2.31 if the unit of measurement is psi (pressure per square inch). Multiplying by 2.31 will convert psi into Head, the unit of measurement you should be using to measure energy. For example, 50 psi is 115.5 Head (50 x 2.31).