Fluid Power Formulas

You have a job to do and remembering every fluid power formula can be tough. Please feel free to use these basic fluid power formulas to make your day a little bit easier.

Basic Fluid Power Formulas

Variable

Word Formula w/ Units

Simplified Formula

Fluid Pressure - P (PSI) = Force (Pounds) / Area ( Sq. In.) P  =  F / A
Fluid Flow Rate - Q GPM= Flow (Gallons) / Unit Time (Minutes) Q = V / T
Fluid Power in Horsepower - HP Horsepower = Pressure (PSIG) × Flow (GPM)/ 1714 HP = PQ / 1714
Pump Formulas

Variable

Word Formula w/ Units

Simplified Formula

Pump Output Flow - GPM GPM = (Speed (rpm) × disp. (cu. in.)) / 231 GPM =  (n ×d) / 231
Pump Input Horsepower - HP HP =  GPM × Pressure (psi) / 1714 × Efficiency HP  =  (Q ×P) / 1714 × E
Pump Efficiency - E Overall Efficiency = Output HP / Input HP EOverall = HPOut / HPIn X 100
Overall Efficiency = Volumetric Eff. × Mechanical Eff. EOverall = EffVol. × EffMech.
Pump Volumetric Efficiency - E Volumetric Efficiency = Actual Flow Rate Output (GPM) / Theoretical Flow Rate Output (GPM) × 100 EffVol. = QAct. / QTheo. X 100
Pump Mechanical Efficiency - E Mechanical Efficiency = Theoretical Torque to Drive / Actual Torque to Drive × 100 EffMech = TTheo. / TAct. × 100
Pump Displacement - CIPR Displacement (In.3 / rev.) = Flow Rate (GPM) × 231 / Pump RPM CIPR = GPM × 231 / RPM
Pump Torque - T Torque = Horsepower × 63025 / RPM T = 63025 × HP / RPM
Torque = Pressure (PSIG) × Pump Displacement (CIPR) / 2π T = P × CIPR / 6.28
Actuator Formulas

Variable

Word Formula w/ Units

Simplified Formula

Cylinder Area - A ( Sq. In.) = π × Radius (inch)2 A  =  π  × R2
(Sq. In.) = π × Diameter (inch)2 / 4 A  = π  × D2 / 4
Cylinder Force - F (Pounds) = Pressure (psi)   × Area (sq. in.) F  =  P × A
Cylinder Speed - v (Feet / sec.) = (231 × Flow Rate (gpm)) / (12 × 60 × Area) v   =  (0.3208 × gpm) / A
Cylinder Volume Capacity - V Volume = π × Radius2 × Stroke (In.) / 231 V = π × R2 × L / 231
(L = length of stroke)
Cylinder Flow Rate - Q Volume = 12 × 60 × Velocity (Ft./Sec.) × Net Area(In.)2 / 231 Q = 3.11688 × v × A
Fluid Motor Torque - T Torque (in. lbs.) = Pressure (psi) × disp. (in.3 / rev.) / 6.2822 T  =  P × d / 6.2822
Torque = HP × 63025 / RPM T = HP × 63025 / n
Torque = Flow Rate (GPM) × Pressure × 36.77 / RPM T = 36.77 × Q × P / n
Fluid Motor Speed - n Speed (RPM)  =  (231 × GPM) / Disp. (in.)3 n  =  (231 × GPM) / d
Fluid Motor Horsepower - HP HP = Torque (in. lbs.) × rpm / 63025 HP  =  T × n / 63025