How to Calculate Hydraulic Cylinder Speed

by | Jul 10, 2026 | single acting cylinder

Hydraulic cylinder speed calculation is the step that connects bore specification, pump selection, and line sizing into a complete system design. A cylinder that generates the correct force but extends too slowly fails the application just as surely as one that is under-powered. Equally, a cylinder that extends at five times the safe speed without end cushioning will damage itself within days. This guide covers the calculation of extension speed, retraction speed, cycle time, and the limits that must not be exceeded.

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The Extension Speed Formula

Extension speed is the rate at which the piston rod travels during extension — determined entirely by the volume of oil entering the cap-end chamber per unit time (pump flow) and the area of that chamber (bore area).

Extension Speed (mm/s) = Pump Flow (L/min) × 1000 ÷ 60 ÷ Bore Area (cm²)

Bore Area (cm²) = π × (Bore Diameter in cm ÷ 2)²

Convert flow: 1 L/min = 1000 cm³/min = 16.667 cm³/s
Convert area: bore in mm → divide by 10 to get cm

Worked example: 63 mm bore cylinder, 15 L/min pump flow.

Bore Area = π × (6.3 ÷ 2)² = π × 9.9225 = 31.18 cm²
Flow rate = 15,000 cm³ ÷ 60 = 250 cm³/s
Extension Speed = 250 ÷ 31.18 = 8.02 cm/s = 80.2 mm/s

The Retraction Speed Formula (Double Acting Cylinders)

Retraction uses the annular area between the bore and the rod — smaller than the full bore area used on extension. The same pump flow filling a smaller area produces a higher speed.

Retraction Speed (mm/s) = Pump Flow (L/min) × 1000 ÷ 60 ÷ Annular Area (cm²)

Annular Area = Bore Area − Rod Area
Rod Area (cm²) = π × (Rod Diameter in cm ÷ 2)²

Continuing the example: 63 mm bore / 36 mm rod, 15 L/min.

Rod Area = π × (3.6 ÷ 2)² = π × 3.24 = 10.18 cm²
Annular Area = 31.18 − 10.18 = 21.0 cm²
Retraction Speed = 250 ÷ 21.0 = 11.9 cm/s = 119 mm/s
Retraction is 119 ÷ 80 = 1.49× faster than extension
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Speed Reference Table — Common Bore and Flow Combinations

Extension speed (mm/s) at common pump flow rates. Bore area used for calculation.

Bore (mm) 10 L/min 20 L/min 30 L/min 40 L/min
50 84.9 169.8 254.6 339.5
63 53.6 107.1 160.7 214.3
80 33.2 66.3 99.5 132.6
100 21.2 42.4 63.7 84.9
125 13.6 27.2 40.7 54.3
160 8.3 16.6 24.9 33.2

Calculating Cycle Time

Full cycle time = (Stroke ÷ Extension Speed) + (Stroke ÷ Retraction Speed) + valve response time. Example: 500 mm stroke, 80 mm/s extension, 120 mm/s retraction, 0.3 s valve response at each end.

Extension time = 500 ÷ 80 = 6.25 s
Retraction time = 500 ÷ 120 = 4.17 s
Valve response = 2 × 0.3 = 0.6 s
Total cycle time = 6.25 + 4.17 + 0.6 = 11.0 s

Maximum Safe Speed and End Cushioning

Standard commercial hydraulic cylinders should not exceed 0.5 m/s (500 mm/s) continuous rod speed without end cushioning. At higher speeds, the kinetic energy of the piston and load at end of stroke must be absorbed somewhere — without cushioning, the piston strikes the end cap at full speed, generating a pressure spike that can exceed 3–5× the working pressure and rapidly destroys seals and hardware. If your application requires speed above 0.3 m/s, specify the cylinder with end cushioning. Contact our engineering team to confirm whether cushioning is required for your bore, stroke, and speed combination.

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Frequently Asked Questions

1. How to calculate hydraulic cylinder speed?+
Extension speed (mm/s) = Pump Flow (L/min) × 1000 ÷ 60 ÷ Bore Area (cm²). Retraction speed (double acting, mm/s) = Pump Flow × 1000 ÷ 60 ÷ Annular Area (cm²), where Annular Area = Bore Area − Rod Area. Example: 80 mm bore, 45 mm rod, 20 L/min pump. Extension speed = 20,000 ÷ 60 ÷ 50.27 = 6.63 cm/s = 66.3 mm/s.
2. Why is retraction speed faster than extension speed?+
On a double acting cylinder, retraction uses the annular area between the bore and the rod — which is smaller than the full bore area used on extension. The same pump flow filling a smaller area produces a higher speed. The ratio of retraction speed to extension speed equals Bore Area ÷ Annular Area. For a 100/56 mm cylinder: extension area = 78.54 cm², annular area = 54.15 cm², so retraction is 78.54 ÷ 54.15 = 1.45× faster than extension at the same pump flow.
3. How does pump flow affect hydraulic cylinder speed?+
Cylinder speed is directly proportional to pump flow — doubling the flow doubles the speed. This is the simplest way to increase cylinder speed without changing the bore size. However, higher flow requires larger lines, a larger directional valve, and increased pump motor power. The trade-off is between speed and system cost and energy consumption.
4. How do I slow down a hydraulic cylinder?+
Add a flow control valve in the supply line to the cylinder — this throttles flow to the cylinder regardless of pump output. Meter-in control (restricting flow into the cylinder) is used for resistive loads; meter-out control (restricting flow out of the cylinder) is used for overrunning loads where the load could pull the cylinder faster than the pump delivers flow. A needle valve in the appropriate line provides simple speed control.
5. What is the maximum speed for a hydraulic cylinder?+
Maximum rod speed for standard commercial hydraulic cylinders is typically 0.5–1.0 m/s (500–1,000 mm/s) for continuous duty. High-speed hydraulic cylinders with cushioning can operate at 2–5 m/s for short strokes. Above 0.5 m/s, end-of-stroke cushioning is strongly recommended to absorb kinetic energy — without cushioning, the piston strikes the end cap with force proportional to the square of the speed, causing rapid seal and hardware damage.