Two-chamber ideal steady-state model

Documented Double-Acting Cylinder Force & Speed Calculator

Calculate piston/annular areas, signed net driving force, ideal speed, return flow and mechanical power for a single-rod cylinder using pressures measured at both cylinder ports.

Both-port pressuresSigned net forceNo hidden efficiency

Calculation / project identifier

Cylinder product / configuration

Diameter unit

Bore diameter D

Rod diameter d

Bore/rod drawing or manufacturer source and revision

Pressure unit

Flow unit

Port-pressure/flow measurement or design source, common pressure-reference basis and revision

Extension state

Cap-end pressure pCE

Rod-end pressure pRE (opposing)

Cap-end inflow QE

Retraction state

Rod-end pressure pRR

Cap-end pressure pRC (opposing)

Rod-end inflow QR

Load, friction, seal, buckling, mounting, pressure-rating and safety review reference

Applicability gate: ideal quasi-steady, rigid geometry and incompressible flow; no leakage, seal/bearing friction, pressure pulsation, acceleration, compressibility, line/cushion losses, side load, buckling, structural stress or efficiency. Enter pressures at the two cylinder ports for each state on the same gauge or absolute reference basis. A negative force means the entered pressure state opposes the named motion.

Ideal documented-state result

Piston area Ap

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Annular area Aa

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Signed extension net force

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Signed retraction net force

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Extension speed

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Retraction speed

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Rod-end return flow during extension

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Cap-end return flow during retraction

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Signed ideal mechanical power, extension

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Signed ideal mechanical power, retraction

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Implemented equations

Ap = πD²/4 ; Aa = π(D²−d²)/4
FE = pCE Ap − pRE Aa ; FR = pRR Aa − pRC Ap
vE = QE/Ap ; QRE,out = vE Aa
vR = QR/Aa ; QRC,out = vR Ap
PE = FE vE ; PR = FR vR

Pressure in pascals times area in square metres gives newtons. Flow in cubic metres per second divided by area gives metres per second. Force times velocity gives watts. The same formulas also show why a single pressure drop multiplied by one area is generally not the net force of an unequal-area single-rod cylinder.

Official manufacturer evidence

Portāls Parker Miller Application Engineering Guide gives a published 2 in bore, 1 in rod, 1000 psi example: 3142 lbf push and 2357 lbf pull when the opposite-side counterpressure is assumed zero. The Parker Designing With Cylinders guide explicitly instructs designers to subtract the opposing chamber force and warns that multiplying a single pressure drop by piston area is incorrect for unequal-area single-rod cylinders. The Parker metric cylinder catalogue states the theoretical relation F(kN)=p(bar)A(mm²)/10000.

ISO 3320 boundary

ISO 3320:2013, edition 3, is Published and was confirmed in 2024. Its public scope establishes metric bore/rod diameter series and corresponding useful-area ratios. It applies only to dimensional criteria and expressly does not apply to functional characteristics. Therefore ISO 3320 is not the source of this page’s force, speed or power equations, and this calculator does not claim ISO conformity. No unlicensed ISO diameter/rod-pair table is reproduced; an ISO dimensional claim must be checked against the licensed standard or controlled manufacturer drawing.

Why the former page was changed

The former JavaScript computed force as p(bar)×A(cm²)/10, which is exactly ten times the correct kN value p×A/100; its own structured-data FAQ used /100 while the visible FAQ and code used /10. It also ignored opposing-port pressure, called the equations “per ISO 3320,” referred to a nonexistent “ISO 3320-2,” accepted partial/negative flow input, embedded unsourced presets/defaults and used 9.81 rather than conventional standard gravity for kgf conversion.

Not a selection or safety calculation: actual available force and motion depend on measured port pressures under flow, friction, leakage, seals, cushions, valves/lines, fluid compressibility, dynamics and load geometry. Verify manufacturer pressure/speed ratings, rod buckling and stress, mounting and pin loads, end stops, guarding, load holding, hose/pipe/valve capacity, relief settings and the applicable system safety requirements.