Horsepower Required to Drive a Pump Gallons Per Minute GPMFormula: GPM x PSI x .0007 = horsepower needed Pounds Sq Inch PSIExample: How many horsepower are needed to drive a 5 gpm pump at 1500 psi? Horsepower (HP)Pump Output Flow (In Gallons Per Minute)Pump RPMFormula: RPM x Displacement ÷ 231 = gpm Pump DisplacementExample: How much oil will be produced by a 2.5 cubic inch pump operating at 1200 rpm?Output Flow (GPM)Pump Displacement Needed for GPM of Output FlowGallons per Minute (GPM)Formula: 231 x GPM ÷ RPM = in3 per revolutionRevolutions per Minute (RPM)Example: What displacement is needed to produce 5 GPM at 1500 RPM?Pump Displacement (Cubic Inches) *Pneumatic and Hydraulic Company, LLC assumes no liability for errors in data nor in safe and/or satisfactory operation of equipment designed from this information.