Hydraulic Cylinder Speed Calculator
This hydraulic cylinder speed calculator finds how fast a double acting cylinder extends and retracts from its bore, rod diameter, and pump flow. Add the stroke and the pressure, and the hydraulic cylinder speed calculator also returns the extend and retract times, the oil volume, and the push and pull forces.
Results
The Hydraulic Cylinder Speed Calculator is part of our Fluids collection. Browse more fluids to size, convert, and check your work alongside this tool.
What the hydraulic cylinder speed calculator does
A cylinder moves as fast as oil fills it. On extend, the pump fills the full bore area; on retract, it fills only the ring around the rod, so the cylinder comes back faster. The hydraulic cylinder speed calculator divides the pump flow by each area to get both speeds, then uses the stroke for cycle times and the pressure for forces.
Hydraulic cylinder speed formula
Speed is flow divided by the area the oil acts on:
D is the bore, d the rod, and Q the flow. With Q in L/min, multiply by 1,000,000 ÷ 60 to get mm³/s, so the speed comes out in mm/s.
Hydraulic cylinder speed calculator example
An 80 mm bore, 45 mm rod cylinder fed 30 L/min, with a 500 mm stroke at 200 bar:
It retracts in 3.44 s, needs 2.513 L of oil to extend, pushes with 100.53 kN, and pulls with 68.72 kN. A 63/36 mm cylinder on 20 L/min extends at 106.9 mm/s.
How to use the hydraulic cylinder speed calculator
Enter the bore and rod diameters in millimeters and the pump flow in liters per minute. Add the stroke in millimeters to get the extend and retract times and the oil needed, and the system pressure in bar to get the push and pull forces. For flow in US gallons per minute, multiply by 3.785 to get L/min.
Reading cylinder speed results
Retract speed is always higher because the rod takes up part of the area; the area ratio tells you by how much. That ratio also means the oil leaving the rod side on extend is less than the pump flow, and the oil leaving the bore side on retract is more, which matters when you size return lines and filters. If the speed is too low, increase the flow or use a smaller bore, but remember a smaller bore also lowers the force at the same pressure.
When to use a hydraulic cylinder flow rate calculator
- Choosing a pump to meet a cycle time
- Checking how fast a log splitter or press will move
- Sizing return lines for retract flow
- Comparing bore sizes for speed and force
- Estimating oil volume needed for a stroke
Common hydraulic cylinder speed calculator mistakes
- Using rod area on extend. Extend uses the full bore area.
- Expecting pressure to change speed. Flow sets speed; pressure sets force.
- Ignoring pump efficiency. Real flow drops a little with wear and pressure.
- Undersized return lines. Retract flow from the bore side exceeds pump flow.
Tips for faster cylinder speed
- Increase pump flow before reducing bore size.
- Size valves and hoses for the largest flow in the cycle.
- Add flow controls for smooth, adjustable speed.
Hydraulic cylinder speed formula in imperial units
US catalogs quote flow in gallons per minute and bore in inches. A gallon is 231 cubic inches, so speed in inches per minute is 231 times the GPM divided by the area in square inches. A 3 in bore has an area of 7.07 in², so 10 GPM moves it at about 327 in/min, or 5.4 in/s. The metric and imperial formulas are the same idea: volume per second divided by area gives distance per second. Pressure does not appear in the speed formula, because flow, not pressure, sets the speed; pressure only rises to whatever the load demands, up to the relief setting. Use the hydraulic force calculator to check that the bore gives enough force at your relief pressure.
Hydraulic cylinder cycle time and pump sizing
To meet a target cycle time, work backward: the slowest stroke sets the flow. If an 80 mm cylinder must extend 500 mm in 3 s, it needs 2.513 L in 3 s, or about 50 L/min. The pump must deliver that flow at the working pressure, and the motor must supply the hydraulic power, flow times pressure divided by efficiency, which the pump power calculator works out. Regenerative circuits send rod side oil back to the bore side on extend, which speeds the cylinder up at the cost of force.
Cylinder speed chart at 20 L/min
Speeds and push force at 160 bar for common ISO bore and rod sizes:
| Bore / rod (mm) | Extend (mm/s) | Retract (mm/s) | Push at 160 bar (kN) |
|---|---|---|---|
| 40 / 22 | 265.3 | 380.3 | 20.11 |
| 50 / 28 | 169.8 | 247.3 | 31.42 |
| 63 / 36 | 106.9 | 158.8 | 49.88 |
| 80 / 45 | 66.3 | 97.0 | 80.42 |
| 100 / 56 | 42.4 | 61.8 | 125.66 |
| 125 / 70 | 27.2 | 39.6 | 196.35 |
Hydraulic Cylinder Speed Calculator FAQ
How do you calculate hydraulic cylinder speed?
Divide the flow by the piston area. 30 L/min into an 80 mm bore is 500,000 mm³/s ÷ 5,026.5 mm², or 99.5 mm/s on extend.
Why does a cylinder retract faster than it extends?
On retract, the oil fills only the ring around the rod, which has a smaller area than the full bore, so the same flow moves the piston faster.
How do I convert GPM to cylinder speed?
In inches, speed in in/min = 231 × GPM ÷ area in in², since one gallon is 231 cubic inches. Or convert GPM to L/min by multiplying by 3.785 and use the calculator.
How do I get the cycle time?
Add the extend time and the retract time from the calculator, plus any dwell at each end. Valve shifting and acceleration add a little more.