Use the the chart to determine the best hose ID for your pumps water flow (GPM).
Basic rule for hose ID.
Generally pressure washers work best with 3/8" ID hose.
Pressure will drop over the length of a hose from friction. The pressure drop across a given hose length is directly proportional. A 50 foot hose will lose exactly 1/2 the pressure of a 100ft hose.
The chart values are valid at all pressure levels.