How to use this calculator
- Enter bore and rod diameter. Use the cylinder bore and piston-rod diameter. Retract speed depends on the annulus area, so the rod diameter matters.
- Enter the stroke length. Use the actual travel that must be completed, not just the cylinder catalog maximum if the machine stops earlier.
- Enter available flow. Enter the pump or valve flow available to this cylinder branch, then set a flow-efficiency allowance if leakage or valve metering is expected.
- Set target stroke time. Enter the one-way target time to back-solve the flow needed for extend and retract.
- Read speed, time and volume. Compare extend and retract speed, one-way time, cycle rate, oil volume and required flow before sizing the pump or valve.
How it works
A hydraulic cylinder's steady speed comes from continuity: flow divided by
the area that is being filled.
v = Q / A
The extend stroke uses the full piston area,
A_p = pi * bore^2 / 4. The retract stroke uses the annulus area,
A_a = A_p - A_rod, because the rod occupies part of the rod-side
chamber.
Stroke time is the stroke length divided by that speed: t = stroke / v Oil volume per stroke is the same area multiplied by stroke length. The required flow outputs run that relation backward: for a target time, flow is chamber volume divided by the target time, corrected by the flow-efficiency allowance. Use the hydraulic cylinder force calculator beside this page when load capacity and rod-area force loss matter, the hydraulic cylinder rod buckling calculator when an extended rod is pushing in compression, and the pump flow and HP calculator when the pump, motor and system pressure need to be checked together. After selecting a line route, use the hydraulic fluid velocity calculator to screen oil velocity before the hose pressure-drop detail.
Worked example
Verified against the live calculator
A 50 mm bore cylinder with a 22 mm rod, 300 mm stroke and 20 L/min pump flow at 95% flow efficiency has about 19 L/min delivered to the cylinder. The piston area is about 1963 mm², so the cylinder extends at about 161 mm/s and takes about 1.86 s for the 300 mm stroke. The annulus area is about 1583 mm², so retract speed is about 200 mm/s and retract time is about 1.50 s. The full extend-plus-retract cycle is about 3.36 s, or about 17.9 cycles/min before acceleration, valve timing and cushion effects. To hit a 5 s one-way target, the extend side needs about 7.4 L/min upstream flow at the same efficiency.
Reference data
Use this hydraulic cylinder speed design worksheet when the job starts from a target stroke time or cycle rate rather than a known cylinder speed. The hydraulic cylinder speed worksheet reference keeps the GPM, bore, rod and stroke-time relationships in a compact lookup path for repeat sizing work.
| Design step | Use this value | Output to check |
|---|---|---|
| Cylinder geometry | Bore, rod diameter and stroke | Piston area, annulus area and swept oil volume |
| Available flow | Pump or valve flow with efficiency allowance | Delivered flow to the cylinder branch |
| Speed screen | Delivered flow divided by piston or annulus area | Extend speed and retract speed |
| Time screen | Stroke length divided by speed | Extend time, retract time and cycle rate |
| Design target | Target one-way stroke time | Required extend and retract flow before pump/valve checks |
| System follow-up | Required flow, pressure, hose size and load | Pump HP, pressure drop and cylinder force context |
Source: Workflow maps this calculator's continuity equations and required-flow outputs; verify pump curve, valve metering, hose pressure drop, cylinder cushions and load-control hardware before final hardware selection.
Frequently asked questions
How do you calculate hydraulic cylinder speed?
Cylinder speed is flow divided by working area: v = Q / A. Extend uses the full piston area. Retract uses the annulus area after the rod area is subtracted, so retract is usually faster than extend for the same flow.
Why does a hydraulic cylinder retract faster than it extends?
On retract, oil fills the rod side of the cylinder. The rod occupies part of the piston area, so the effective annulus area is smaller than the full bore area. The same flow through a smaller area gives higher speed.
How do I calculate hydraulic cylinder stroke time?
First calculate speed from flow and area. Then divide stroke length by speed: time = stroke / speed. This calculator does that separately for extend and retract, and also returns the combined extend-plus-retract cycle time.
How much flow do I need for a target stroke time?
Oil volume per stroke is area times stroke length. Required flow is that volume divided by target time, with the entered flow efficiency allowance applied. The page reports separate required flows for the extend and retract strokes.
How do I use this as a hydraulic cylinder speed design calculator?
Start with bore, rod and stroke, enter the pump or valve flow available to the cylinder, then compare extend/retract speed with the target stroke time. If the target is not met, use the required-flow outputs before checking pump horsepower, valve capacity and hose pressure drop.
Does this include valve restrictions or cylinder cushions?
Only through the simple flow-efficiency allowance. It does not model meter-in or meter-out valve settings, cushion needles, acceleration ramps, load overrunning, counterbalance valves, hose pressure drop or compressibility.
Can I use GPM and inches?
Yes. Toggle Imperial in the header and the inputs switch to inches and GPM while the internal calculation remains unit-consistent.
Method & assumptions
- Steady, incompressible flow model: speed is delivered flow divided by piston or annulus area.
- Flow efficiency is a simple first-pass allowance for leakage, valve metering, cushion restriction and small line losses. Use 100% for ideal delivered flow.
- Acceleration, deceleration, cylinder cushions, load-induced overrunning, counterbalance valves and flow-control valve details are not modeled.
- Pressure, force and rod buckling are not checked on this page. Use the linked force, rod-buckling and pump-power calculators before choosing hardware.